Translation
In this way you also, if through the tongue you do not give well-marked
Go to footnote numberspeech, how will it be known what [is] being spoken? For you will be speaking into air.
Paraphrase
It is the same with you and the sounds you make. If you keep using this form of tongues you have invented which includes unclear sounds, and if you keep doing it in public instead of in private, how will those who hear you know what you are saying? You will be speaking to no one, which would violate the form of tongues seen on Pentecost as well.
Footnotes
1
This word comes from the preposition “well” and the verb “to give a sign, indicate, make known.” Together they mean “well-marked, clear, intelligible, easy to understand.”