Судя по макету тут как минимум 3 варианта. Если придерживаться вашей версии, что все в одном блоке dashboard, то будет примерно такая картина с модификатром (ключ_значение):
<div class="dashboard">
<div class="dashboard__container">
<div class="dashboard__header">
Your channels
</div>
<div class="dashboard__btn btn">
<div class="btn__ico"></div>
<div class="btn__content">Create a chanell</div>
</div>
<div class="dashboard__list">
<div class="dashboard__item dashboard__item_type_1">
<div class="dashboard__pic dashboard__pic_size_smal">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title dashboard__title_size_small">lorem</div>
<div class="dashboard__url">lorem</div>
</div>
</div>
<div class="dashboard__item dashboard__item_type_small">
<div class="dashboard__pic dashboard__pic_size_smal">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title dashboard__title_size_small">lorem</div>
<div class="dashboard__url">lorem</div>
</div>
</div>
<div class="dashboard__item dashboard__item_type_small">
<div class="dashboard__pic dashboard__pic_size_smal">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title dashboard__title_size_small">lorem</div>
<div class="dashboard__url">lorem</div>
</div>
</div>
</div>
</div>
<div class="dashboard__container">
<div class="dashboard__header">
Subscriptions
</div>
<div class="dashboard__list">
<div class="dashboard__item">
<div class="dashboard__pic">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title">lorem</div>
<div class="dashboard_desc">lorem</div>
</div>
</div>
<div class="dashboard__item">
<div class="dashboard__pic">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title">lorem</div>
<div class="dashboard_desc">lorem</div>
</div>
</div>
<div class="dashboard__item">
<div class="dashboard__pic">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title">lorem</div>
<div class="dashboard_desc">lorem</div>
</div>
</div>
</div>
</div>
</div>
Второй вариант это миксовать с родителем:
<div class="dashboard">
<div class="dashboard__container subscribers">
<div class="dashboard__header">
Your channels
</div>
<div class="dashboard__btn btn">
<div class="btn__ico"></div>
<div class="btn__content">Create a chanell</div>
</div>
<div class="dashboard__list subscribers__list">
<div class="dashboard__item subscribers__item">
<div class="dashboard__pic subscribers__pic">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title subscribers__title">lorem</div>
<div class="dashboard__url">lorem</div>
</div>
</div>
</div>
</div>
<div class="dashboard__container subscribtions">
<div class="dashboard__header">
Subscriptions
</div>
<div class="dashboard__list">
<div class="dashboard__item">
<div class="dashboard__pic">
<img src="" alt="" class="dashboard__img">
</div>
<div class="dashboard__content">
<div class="dashboard__title">lorem</div>
<div class="dashboard_desc">lorem</div>
</div>
</div>
</div>
</div>
</div>
</div>
3-й вариант и порой самый уместный это не обращать внимание на то что блоки якобы похожи. Это разные блоки по своему назначению, а значит их смело можно делать разными и в разметке. Ведь если у них разное предназначение, значит возможны и значительные отличия в будущем:
<div class="dashboard">
<div class="dashboard__subscribers subscribers">
<div class="dashboard__header">
Your channels
</div>
<div class="dashboard__btn btn">
<div class="btn__ico"></div>
<div class="btn__content">Create a chanell</div>
</div>
<div class="subscribers__list ">
<div class="subscribers__item">
<div class="ubscribers__pic">
<img src="" alt="" class="subscribers__img">
</div>
<div class="subscribers__content">
<div class="subscribers__title">lorem</div>
<div class="subscribers__url">lorem</div>
</div>
</div>
</div>
</div>
<div class="dashboard__subscribtions subscribtions">
<div class="dashboard__header">
Subscriptions
</div>
<div class="subscribtions__list">
<div class="subscribtions__item">
<div class="subscribtions__pic">
<img src="" alt="" class="subscribtions__img">
</div>
<div class="subscribtions__content">
<div class="subscribtions__title">lorem</div>
<div class="subscribtions_desc">lorem</div>
</div>
</div>
</div>
</div>
</div>
</div>
Каждый из этих вариантов можно еще доработать