To overflow or brim over; to flood. Also used figuratively for emotions or places filled to capacity. (Often written in kana.)
大雨で川が溢れた。
The river overflowed because of the heavy rain.
会場は観客で溢れていた。
The venue was overflowing with spectators.
彼の胸には喜びが溢れていた。
His heart was overflowing with joy.
棚から花が溢れるように飾られていた。
The shelves were decorated as if flowers were spilling over them.