The court ruled in favour of the plaintiff and the defendant had to pay court costs.

wont' that be an appeal?

The wording of the question is too cryptic - however - it appears that the Plaintiffs claim was dismissed due to the plaintiff's lack of prosecution (e.g.: The plaintiff failed to appear in court to press their case -or- the plaintiff withdrew their case- etc).

A plaintiff is the party who brings a civil lawsuit against another party, known as the defendant, seeking legal remedy or compensation for harm or breach of contract. The plaintiff is responsible for proving their case against the defendant in court.

The Plaintiff.