A comma splice incorrectly connects independent clauses with a comma.

Here are some examples from the Purdue OWL Engagement website:

Comma Splice: My family bakes together nearly every night, we then get to enjoy everything we make together.
•Correction 1: My family bakes together nearly every night. We then get to enjoy everything we make together.

The comma splice has been corrected by breaking the sentence into two separate sentences.
•Correction 2: My family bakes together nearly every night, and we then get to enjoy everything we make together.

The comma splice has been corrected by adding a coordinating conjunction and a comma.
•Correction 3: After my family bakes together nearly every night, we get to enjoy everything we make together.

The comma splice has been corrected by adding a subordinating conjunction and a comma.