It's not about knowing the language. It's about how well you understand the language. When I moved to Canada, I heard many words from people. When I translated those words into my mind, it didn't give me the real meaning. After living for several years, now I understood some of those words, what they wanted to say to me. Or I understand, what I shouldn't say to them.
Sometimes, it's not words. People did something in front of me to say something. I didn't get that. Now I know about some of those from movies or from personal experience.
My cultural background is different from Canada. There are many things that people expect here like there are many ways to say to an unknown person or to offer something or showing interest. But I'm kind of a fool in these issues. Even in my home country, I didn't understand many of those offers.
In our country, when we started to know any person, or any colleague or classmate, we easily can ask the contact number. Here when a person asks the contact no, without any official purpose, it means that person wants to date you. So, don't ask contact no, unless you really need it and explain why you need it before you ask for it.
In our country, if we get a know a person, we asked them to visit our home and have a meal with us. Here you will or should only ask like that if that person became a very close friend. Otherwise, that person may think, you have some other intention to invite.
If, out of blue, any colleague or a known person came to you and say “Thank you “ then leave before you answer, it doesn’t mean they are happy. It means that the person is very angry on a specific actions of you.
Now about the sign to get close ... hmm nope, maybe some other day I will talk about it ;)