Seven long or cylindrical objects — the counter '本' used for counting long, thin items.
傘が七本も壊れてしまった。
As many as seven umbrellas broke.
箸を七本洗ったら、もう十分だ。
After washing seven chopsticks, that's enough.
苗木を七本庭に植えた。
I planted seven saplings in the garden.