How come this sentence is starting with "but"? Does it mean "however" here? I don't get the context of using "but" here.
She uses "but" at the beginning of this sentence because this sentence is an interjection, which is an abrupt comment. Therefore, the use of "but" here tells the listener that what she is about to say is different from what she was previously saying. For example here, she was talking about how healthy the toothpaste she uses is, and then used "but" to say "But I really like this toothpaste" because the fact that she likes the toothpaste is somewhat unrelated to how healthy it is. Using "but" like this is only done in conversational English, not written English, because it is not grammatically correct to start a sentence with "but".