Right-side
荅 supplies the sound: dá shifts to tǎ with an aspiration/tone shift.
塔 is a transliteration of Sanskrit 'stūpa' — a Buddhist relic mound — so the phonetic was chosen to match 'tā/tǎ' for the foreign word, and
土 added to mark it as a structure of earth.
荅 here is a sound carrier.