Honest
Upfront, Obedient
な adjective
Remember how 直 can also mean "direct?" Well, if someone has an element of directness to them, they're probably a really honest and upfront person.
素直 usually describes someone who's sincere, emotionally open, willing to listen, and not stubborn. In some contexts, it can also imply someone is obedient or compliant. For example, a child who always does what they're told without objection might be called 素直.
The reading for this is a bit of a weird one. It uses on'yomi for 素, then it uses the kun'yomi for 直. You know both readings, but it's all a little strange, so here's a mnemonic help you:
To present yourself as an honest person, you should hurry up and change into a suit (す) now (なお). We all know that people in suits look more honest and upfront, so go get suited up now!
素直に認めろよ。
Just be honest and admit it.
君の素直な気持ちが聞けてうれしいよ。
I'm glad I could hear your honest feelings.
人のアドバイスを素直に受け入れられる素直さって大事だよね。
It's important to have the openness to accept advice from others.