To "tolerate" something that you don't like means that you put up with it. You let it happen, even though you don't like it.
If there's something that you don't like, but you're able to accept it reluctantly, say "I can tolerate ___":
A: Do you eat shrimp?
B: I can tolerate it, but I don't love it.
I can tolerate a long commute as long as I'm able to get a seat on the train.
When you use the word "tolerate in a negative sense, though, it has a stronger meaning. You use "can't tolerate ___" to talk about things that you not only dislike, but also make you angry:
I can not tolerate laziness.
I can't tolerate people who brag.
As in these examples, "can't tolerate ___" often describes people's behavior.