KanjiJLPT N2
Surround

surround, besiege, store, paling, enclosure, encircle, preserve, keep

Mnemonic

A giant mouth gapes wide and slams shut to surround an entire well. Its lips seal tight around the stone rim, enclosing it completely. Nobody can draw water anymore—the well is locked inside the mouth's fleshy grip, hemmed in from every direction with no escape.
Additional thoughts
The mouth radical forms the outer enclosure (口→囗), while the well radical (井) sits trapped inside. Picture a cartoonishly huge mouth clamping down over a village well like a lid, perfectly capturing the idea of total encirclement.
Quick recall
A huge mouth clamps shut to surround a well, sealing it inside completely.

Details

The keyword for 囲 is surround. This kanji conveys the idea of enclosing or encircling something on all sides, creating a boundary around it. It is used to express the act of surrounding, besieging, or fencing in, as well as the concept of an enclosure or perimeter. The character carries the sense of something being completely enclosed or hemmed in from every direction.
On'yomi
Kun'yomi
かこ.む、かこ.う、かこ.い