The basic grammar for an exclamation of praise is
[person] is good at [activity noun / gerund form of verb]
When praising a person in this way, you must describe the activity as a noun rather than a verb, but you can turn verbs into simple nouns by using gerunds. Alternatively you can use a regular noun activity instead.
An example for a sport as a noun:
He's good at football!
Some examples for specific skills using verbs as gerund-nouns:
He's good at passing!
He's good at scoring!
Note the contraction he's instead of he is, such contractions are very common in exclamations, rather than saying the entire word phrase.
Saying he's good is a fairly generic and low-intensity way to praise somebody's skill, and it's common to see higher degrees of intensity and exaggeration used in everyday speech. Examples:
Another point is that context is frequently implied in exclamations rather than stated directly. So instead of he's amazing at football, if the context of who you and what you are talking about is obvious, it's very common for people to just say he's amazing. You can always explicitly state the full context if you wish, that is grammatically fine, but you will commonly find English speakers do not bother to.
Additionally, exclamations in English often make use of slang, which varies by region, age, and social group. The variety of slang for praising people is extremely diverse and you'll have to pick it up as you go.
I also want to mention there are other ways to do exclamations of praise, this is by no means the only way to do it in English. You can use the word what to form simple exclamatory statements about people or actions. Example:
What a footballer!
What a pass!
What a goal!
The meaning of these exclamations is that you find the person or action to be impressive. You can also add some of those adjectives I mentioned earlier into this form as well:
What an amazing footballer!
What an incredible pass!
And so on. There are other forms as well, but these are basic ones that you will see often. You can also use them for negative exclamations as well, just say bad at wherever you would normally say good at and use negative adjectives instead of positive ones in general and it works the same way.