Questions & Answers about Petrecerea începe seara.
Because petrecerea is the definite form: the party.
In Romanian, the definite article is usually attached to the end of the noun, not written as a separate word like English the.
- petrecere = a party / party
- petrecerea = the party
So here, petrecerea is the subject of the sentence: the party.
Începe is the 3rd person singular present tense of the verb a începe, meaning to begin / to start.
Here it agrees with petrecerea, which is singular:
- eu încep = I begin
- tu începi = you begin
- el/ea începe = he/she/it begins
- noi începem = we begin
- voi începeți = you all begin
- ei/ele încep = they begin
So Petrecerea începe = The party begins / starts.