God understands when one speaks in tongues...
1 Corinthians 14:2 For anyone who speaks in a tongue[a] does not speak to men but to God. Indeed, no one understands him; he utters mysteries with his spirit.
To understand the purpose of a prayer language(SEE BELOW)
“26 So too the [Holy] Spirit comes to our aid and bears us up in our weakness; for we do not know what prayer to offer nor how to offer it worthily as we ought, but the Spirit Himself goes to meet our supplication and pleads in our behalf with unspeakable yearnings and groanings too deep for utterance.
27 And He Who searches the hearts of men knows what is in the mind of the [Holy] Spirit [what His intent is], because the Spirit intercedes and pleads [before God] in behalf of the saints according to and in harmony with God's will.”
Romans 8:26-27 AMP
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John 14:16 And I will ask the Father, and he will give you another Counsellor to be with you for ever 17 The Spirit of truth. The world cannot accept him, because it neither sees him nor knows him. But you know him, for he lives with you and will be in you.