also: なんよりも
adverb
more than anything; above all else
Used to emphasize that something is the most important or the highest priority. Often placed at the beginning of a sentence or before the main verb.
健康は何よりも大切です。
Health is more important than anything.
何よりも、家族の安全が第一だ。
Above all else, the safety of my family comes first.
何より is a shorter, more casual form with the same meaning. 何よりも is slightly more emphatic.
Combination of 何 (what) + より (than) + も (also/even), literally 'even more than what', used adverbially to mean 'more than anything'.