In Japan, people use honorific suffixes after names. This is very rude to forget those suffixes, so be careful.
You could find below, very common suffixes you could use for your everyday life.
-SAMA / さま / 様
(ex : Yamamoto-sama )
This is super polite suffixe. If you work in Japan, you should use it with customers, or with business partners, people from other companies.
-SAN / さん
(ex : Yamamoto-san)
This is probaly the most used suffixe. Very neutral, you could use it anytime with people you don't really know, or people you've just met.
-KUN / くん
This is an informal suffixe for men or boys younger than you. You could use it for people you are close with.
-CHAN / ちゃん
This is an informal suffixe used for women you are close with, or younger than you. This also might be used for family members, very close friends, or for children.
When you say your name, or speak about yourself, this is important to do not use any suffixes, but only your name.
For example, if your name is Yamamoto, on the phone you could say "Yamamoto desu" (it's Yamamoto) and NOT "Yamamoto-san desu".
Another thing you have to be careful, is when you speak about someone from your company to a client (or someone extern to your company). Even if the person from your company is your superior, you coulnd't use a suffixe after his name.
Client to you : Yamamoto-SAMA ga irasshaimasu ka ? /Is Yamamoto there ?
You : Yamamoto ha Tokyo ni irasshaimasu... /Yamamoto is in Tokyo...
Even if Yamamoto-san is your colleague, or superior, and you usually use a suffixe, when someone out of your company is asking, you couldn't use SAMA or SAN regarding an employee, because you have to give an humble image of your company.