“Psikis” in English can be translated as:

• Psychological — relating to the mind, emotions, or mental processes. (most common/formal)
• Psychic — relating to supposed extrasensory or supernatural abilities; not usually the right translation for Indonesian psikis.
• Mental — relating to the mind or mental state, depending on context.
• Psychological state — keadaan psikis
• Psychological condition — kondisi psikis
• Psychological effects — dampak psikis
• Psychological response/reaction — respons/reaksi psikis

Example:
“Dampak psikis dari kejadian tersebut” → “The psychological effects of the incident.”

If you mean “psikis” in contrast with “fisik”, the natural English pair is usually “psychological/mental” vs. “physical.”