‘Hello’ is the basic word to be polite in a country and introduce a conversation. (well… In France it’s the case). But as well as in English we have different way to say it in French, according to when or to whom you are talking to.
Imagine, it’s the morning, you’re going to take your breakfast at your hotel or in a café, you’re going to say ‘bonjour‘ to those you will see. You can say ‘bonjour’ until 5 p.m.
Normally, after 5 p.m, to say ‘hello’ you’re going to say ‘bonsoir‘. (I usually use ‘bonjour’ whenever I need to say ‘hello’ so I promise nobody will grumble if you use ‘bonjour’ at 7 p.m !) ‘bonsoir’ is just more appropriate according to the moment of the day, you are closer to the evening than to the beginning of the day !
If you are with French friends, you can use ‘salut‘, which can be compared to ‘hi’ whenever you meet the person.
Now you can start a conversation like a real French !