This is the 719th most frequent Japanese word.
上がっ
The word "上がっ" is a conjugated form of the verb "上がる" (agaru), which means "to rise," "to go up," or "to ascend."
In this sentence, '上がっ' refers to an increase in excitement or mood.
テンションが上がった。
The excitement elevated.
Here, '上がっ' describes the physical act of moving upwards, in this case, climbing stairs.
階段を上がったところに部屋がある。
There is a room at the top of the stairs.
In this context, '上がっ' is used to indicate an increase in pitch or tone.