The sentence:

Qu’est ce que c’est ?

Means “what is this?” (literally: “what is this that it is”)

In older times, a simpler sentence would have been used:

Qu’est-ce ?

but it is now written/formal French.

The pronoun ça (a shortened form of cela) means this/that.

Here is is appended by the speaker to indicate what the question is referring to, usually by pointing the object.

It should be separated by a comma from the rest of the sentence:

Qu’est-ce que c’est, ça ?

or by another que:

Qu’est-ce que c’est que ça ? often colloquially pronounced /kɛseksa/

The next sentence is incorrect:

Qu’est ce que ça ?

Colloquial French can be:

C’est quoi, ça ?

Slang might be:

Quésaco / Kézaco ? (from Occitan Qu’es aquò)