Meaning: The first day of the week was extremely good.
Choice of Words: Sunday is the seventh day of the week. Perfect means extremely good or without any faults.
Alternative Expressions
Sunday was an amazing day.
Meaning: This sentence tells us that the day of Sunday was very surprising and wonderful.
Choice of Words:Sunday is the name of a day of the week. Was is a verb that tells us about something that happened in the past. Amazing means causing great surprise or wonder.
We had a great time on Sunday.
Meaning: This sentence tells us that the speaker and one or more other people had a very enjoyable and memorable time on Sunday.
Choice of Words:We is a pronoun that refers to the speaker and one or more other people. Had is a verb that tells us about something that happened in the past. A great time means a time that is enjoyable and memorable.