Parallel
1 Corinthians 14:9
King James Version (1769 Blayney revision, with Apocrypha) · Berean Standard Bible
So likewise ye, except ye utter by the tongue words easy (note: Gr. Significant) to be understood, how shall it be known what is spoken? for ye shall speak into the air.
So it is with you. Unless you speak intelligible words with your tongue, how will anyone know what you are saying? You will just be speaking into the air.