great job

You say this when someone does something really well. You say it to your children, your employees, your team mates, or anyone who you feel comfortable complimenting in this way.

It's more common to say "good job". So when you say "great job" it sounds like an even stronger compliment.

A slightly more proper way of saying this is:

"You did a great job."

But just "Great job" is more common in spoken conversation.

If you want to specify what you're complimenting the person for, you can say "great job on (something)":

Great job on that presentation, Betty.

guys

In English, there's not a really good word for addressing a group of people. If you're talking to one person you say "you":

How are you?

But there's some disagreement about what to say to a group of people. English speakers use different expressions depending on the region and dialect, but one common expression is "guys". For example, at a restaurant with a large group of friends you can say:

Hey guys, are you ready to order?

"Guys" technically means a group of men, but it's usually OK to use it for mixed groups of men and women, or even for groups of all women.

In very formal situations, avoid calling a group of people "guys". Instead, use a phrase like "everyone":

Everyone, thank you for coming.

Keep up the good work.

You say this when someone is doing a good job and you want to encourage them to continue. It's used by a person of higher authority talking to a person under them. For example, a teacher to a student, a coach to a player, a manager to an employee, or a parent to a child. If you use it to a person who's not under your authority, it can sound rude.

You usually say this phrase at the end of the conversation, after you have talked about the good things that the person did. For example:

• Boss: Katie, I really like the way that you designed this. The colors really work well together. I think this is going to look great.
• Katie: Oh, thank you.
• Boss. You've really been doing some great stuff lately. Keep up the good work.

A good response to this is, "Thanks, I will."