salty, salt
鹺 centers on saltiness: the taste of salt, or salt itself as a substance. The two given meanings are direct applications of this core idea.
鹺 combines 鹵 (salt) with 差, which likely contributes the sound. The character is a phono-semantic compound expressing saltiness.
The left side 鹵 represents salt, and the right side 差 looks like a pile of salt crystals. Together they make the idea of salty salt.
For サ, imagine a salt shaker full of salt: the first syllable of 'salt' and 'shaker' both cue サ, and the kanji is all about salt.