<ul class="product-item_params">
<li>
<span class="product-item_params_name">Бренд:</span>
<span class="product-item_params_value">Домик </span>
</li>
</ul>
from bs4 import BeautifulSoup
soup = BeautifulSoup('''<html lang="en"><body><ul class="product-item_params">
<li>
<span class="product-item_params_name">Бренд:</span>
<span class="product-item_params_value">Домик </span>
</li>
</ul></body></html>''', 'html.parser')
print(soup.find('span', {'class': 'product-item_params_value'}).text)