エキ, ヤク, ま.す, まし, ます

benefit, gain, profit, advantage

JLPT1 G5 S10 F674

The relevant seal inscription form is dish/plate/bowl + the character (water) turned on its side, indicating liquid filling a container → *fill* → *advantageous*; *benefit* (← possess full resources) → *profit* (← employ one's advantages to gaining profit). Note a variant form 益.

[Full Kanji Etymology List]