How do you distinguish the two meanings of word jealous?

There aren't two meanings, there's only one.  Jealousy is a FEELING, an emotion. Isn't there an equivalent word in your language? 

only by context, as with any words that can have different meaning according to different situations.  Absent any context, I would ask what you actually mean, because out of context, I cannot know.  I can only know what you say.  If you don't say enough, I cannot know.

Normally the first meaning applies unless you are talking about someone's spouse or lover. So if you say "my friend is jealous of me" one would assume the first meaning. If you did mean the second, you would need to clarify by it by saying something like "my friend is jealous of the new friends I've made at school."

On the other hand if you said "he is jealous of his wife" one would assume the second meaning. If you meant the first you again would clarify it by something like "he is jealous of his wife's professional success."

1. My husband is jealous that I might cheat on him.

2. I am jealous of my neighbor, who is richer than we are.

Like many other words, you need context to know the meaning.  In the example you give, it could be either way.