Spiritual
Mental, Emotional
な adjective
Your 精神 is your spirit. If you add 的 to it, your spirit becomes spiritual.
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of your kanji you'll know how to read this as well.
精神的に病んでいた時、毎日一人で公園をブラブラしていました。
When I was mentally troubled, I was wandering aimlessly around the park alone every day.