Romans 8:26 says that when we do not know how to pray, the Spirit intercedes for us with what?

Answer: Wordless groans

The Spirit helps us in our weakness and intercedes with groans too deep for words (KJV: groanings which cannot be uttered).

“In the same way, the Spirit helps us in our weakness. For we do not know how we ought to pray, but the Spirit Himself intercedes for us with groans too deep for words.”— Romans 8:26 (BSB)