Indispensable
Required, Essential
Something that's certainly necessary is something you can't live without. It's indispensable. And it's required by you to keep on living.
ひっす
This is a jukugo word that uses the on'yomi readings of the kanji. You should be able to read this on your own.
デフォルトでは、名前と生年月日、メールアドレスの入力が必須になっています。
By default, you’re required to input your name, birthdate, and email address.