Completely full (of a container or space); nothing more can be added — used for cups, rooms, schedules, etc.
コップにジュースが満杯に注がれていたので、注意して持ってください。
The glass was filled to the brim with juice, so please carry it carefully.
朝の電車は満杯で、次の電車を待つ人が多かった。
The morning train was packed, and many people waited for the next one.
今週は仕事で予定が満杯だから、週末しか時間がない。
My schedule is completely full with work this week, so I only have time on the weekend.