A comma splice is the mistaken use of a comma to separate two independent clauses (two sentences that can stand on their own).
We saw Lisa at the store, she was wearing a red shirt.
This is a comma splice. The comma should be a semicolon
This is correct;
We saw Lisa at the store; she was wearing a red shirt.
You can also include a conjuction to fix a comma splice:
Comma Splice: She was being rude, everyone noticed it.
Semicolon: She was being rude; everyone noticed it.
Conjunction: She was being rude, and everyone noticed it.
Bien