This ad is part of a poster campaign from DePaul, a charity working to support homeless and marginalised people around the world. You can see the other ads here and here. The ad informs us that 5 billion (euros, dollars?) is spent on animals every year, while only 0.2 is spent on the homeless, and shows homeless people dressed up in animal costumes, with the tagline "Sometimes we'd rather be treated like animals".
The ad cleverly turns a common English expression on its head. Usually, If you treat someone like an animal, you treat them very badly. However, in the case of homeless people, animals are treated better than they are (in financial terms, at least), hence the tagline.
We'd rather is a contraction of "We would rather", and means "We would prefer to". • We'd rather stay at home tonight. See here for more on this point.
Get your students to come up with their own posters to raise awareness about homelessness.