"Likewise the Spirit also helpeth our infirmities: for we know not what we should pray for as we ought: but the Spirit itself maketh intercession for us with groanings which cannot be uttered. And he that searcheth the hearts knoweth what is the mind of the Spirit, because he maketh intercession for the saints according to the will of God." (Rom 8:26-27)
I heard a story once about a woman who had decided to learn Hebrew. Her reason for this, so she said, was to be able to speak to God in His own language. It's rather silly, of course, but is fairly typical of how some people think of speaking to God.
We need to always remember that God is Spirit and is worshipped in spirit. When God communicates to us it is by a spiritual language. However, we think in language. Just try to think without words sometime and see how difficult it is. Even more difficult is to try and communicate without words. So, in our mind we translate, so to speak, the spiritual knowledge into words that we know. For example, if God gives the word "UTTER DESTRUCTION" to someone, that person will probably imagine something familiar to them. For one person it might be understood as world-wide plague, while to another some natural disaster. Prophecy often works that way. The prophet has to translate the spiritual message into some image that can be communicated. So, it gets pretty confusing some times.
This is one reason two people can be expressing the same spiritual thing in very different words. It's important to remember that the important thing is the spiritual knowledge not so much the words or images that are used. That can be difficult, especially when the person is using words we are not familiar with, or, using familiar words in a way we are not used to.
We have the same situation in our prayers. We will speak to God using the language that we know. But, sometimes it is very difficult to find just the right words to express what we feel. There are of course many prayer books available so that you can just read a prayer someone else wrote. That seems to be helpful to some people. Others (myself included) tend to just make it up as they go, as if they are having a conversation with God. Whatever the case, we have to remember that it is not the particular words we use that get God's attention.
That's the meaning I get from these verses Paul wrote in Romans. We may be in such a beaten down condition that we can't even think straight and it seems like we just can't find words to pray. The promise we have is that God looks at the intention in our mind. That's what the phrase "knoweth the mind" is referring too. The word translated mind means "intention" or "purpose" and that is what the Spirit is hearing when we pray, and then makes intercession for us.
I know there are times when I just can't seem to find the words to express what I need to say to the Father, or to find the words for the things that I should ask. But, I remember these verses and know that if I just get my heart and intent going in the right direction, no matter how clumsy the words are, the Holy Spirit will jump in and help. If all one can do is just cry out with a groan, that can be enough.