That's not a quote from Trump, but rather a quote from an article describing what he said.

This is what he said:

"When Mexico sends it people, they're not sending their best. They're not sending you. They're sending people that have lots of problems, and they're bringing those problems with us. They're bringing drugs. They're bringing crime. They're rapists. And some, I assume, are good people,"

Now I'm not going to defend the delivery. I don't think Mexico "sends" people in general, but it may happen (e.g. Mariel boat lift).

However, if the message is that bad people from Mexico are getting into the country and that should stop, I don't think anyone could argue that. Could it actually be stopped? Probably not, but it's worth trying.