You know, I mean, like...

Japanese students studying in the US learn English from their friends at college, so, it is not strange that they speak like college students.

Some Japanese people who can speak English to some extent tend to use phrases like "you know," "like," and "kind of." If you are asked not to use them, you may need to change the way you speak. I think, though, that you don't have to take too personally. The speech that contains those words could sound like that of American college kids. Anyway, non-native speakers' speech is often criticized by other elements, so you could say that it had been very very hard until you became able to speak like college kids. And also it is true that the words like "like" and "you know" are very convenient when it comes to the situation in which you need time to find an appropriate word.

As long as you are non-native speakers, you often need time to find appropriate words or expressions. "You know" or "like," may give some time for it.

By the way, I need to mention the usage of "I mean," which could slightly different than the cases of "you know" or "like." My friend clearly told me that I should not use "I mean" when I was looking for an appropriate word. The reason would be that if listeners hear "I mean," they will think that they can forget what they have heard before. In other words, "I mean" is used for redefining what they have said before.

You shouldn't identify "I mean" with "you know."