कुत्ता करतब करता है।

• कुत्ता = dog
• करतब = trick / stunt / feat
• करता है = does / performs

A very literal gloss would be: The dog trick does.
Natural English is: The dog performs tricks or The dog does tricks.

Because करतब is a noun, while करता is part of the verb.

Hindi very often uses a noun + करना pattern:

• काम करना = to do work
• कोशिश करना = to make an effort / try
• करतब करना = to do tricks / perform tricks

So here:

• करतब = the thing being done
• करता है = does

है is the present-tense auxiliary is. In this sentence, करता है works together as the normal present habitual form.

So:

• करता by itself is not usually the full standard sentence here
• करता है = does / performs

In standard Hindi, you normally need है in this kind of sentence.

Usually, करता है is the habitual form. It often means:

• the dog does tricks
• the dog performs tricks
• the dog habitually or generally does this

If you want to say the dog is doing tricks right now, Hindi more often uses the progressive:

• कुत्ता करतब कर रहा है। = The dog is doing tricks right now.

Because the subject कुत्ता is masculine singular.

In the habitual form, the verb agrees with the subject here:

• masculine singular → करता है
• feminine singular → करती है
• masculine plural → करते हैं

So with कुत्ता (dog, masculine singular), करता है is the correct match.

Because करतब is one of those Hindi nouns whose direct singular and direct plural look the same.

So:

• एक करतब = one trick
• दो करतब = two tricks

The form changes in other contexts, but not here.
That means करतब can be understood from context as trick or tricks.

Hindi usually does not use articles like English a/an/the.

So कुत्ता can mean:

• a dog
• the dog
• dogs in a generic sense, depending on context

If you want to be more specific, Hindi uses other words:

• एक कुत्ता = a dog
• यह कुत्ता = this dog
• वह कुत्ता = that dog

Yes. This sentence follows the normal Hindi pattern of putting the verb near the end.

So the order is:

• कुत्ता = subject
• करतब = noun/complement
• करता है = verb phrase

Hindi is often described as SOV:

• Subject + Object/Complement + Verb

That is why कुत्ता करतब करता है sounds natural.

You change the verb to match the subject.

• कुतिया करतब करती है। = The female dog performs tricks.
• कुत्ते करतब करते हैं। = The dogs perform tricks.

So the important changes are:

• करता है → masculine singular
• करती है → feminine singular
• करते हैं → plural / masculine plural

Yes, कुत्ता करतब करता है is understandable and natural enough.

Another very common expression is:

• कुत्ता करतब दिखाता है।

That literally means The dog shows tricks, but in natural English it also means The dog performs tricks.

A rough difference:

• करतब करता है = focuses on doing tricks
• करतब दिखाता है = focuses on showing tricks to others

Both can work, depending on the situation.