Many autistics find difficulty accessing vocabulary. This can be a type of aphasia & perfectly normal as we use different lobes of our brain to reason and understand due to what's thought to be simply a different type of connectivity in our brain. Many studies suggest music can be the key to growth. While young, are all kinds of ways one can communicate: encourage art, theatre movement/dance (even yoga/judo), and yes - music. But also, a picture book encyclopaedia can help, as can precision with pragmatics- often these difficulties might mean we use the wrong word to convey a thing. Being imprecise as one grows can have a negative effect, impacting relationships, especially if the understanding of a thing is muddled up with something it's not.
Telling a friend I feel alone can make them feel offended, a better word might be 'isolated' or misjudged. In the extreme case, misunderstanding what a matter actually is and how it's identified can become a legal issue or a mis-accusation.
https://en.wikipedia.org/wiki/Anomic_aphasia
Some helpful tips with communicating: https://1specialplace.com/2020/12/23/speech-tips-for-anomic-aphasia/
Other types of difficulty might also occur with the phonetics: words that sound similar can be genuinely mixed up. In my house, we're always consulting google! It can be one of the most intensely frustrating things to have a perfect vision in ones imagination and not be able to communicate it. Sometimes the detail is so overwhelming, how does one begin? Children will have less of an ability to handle this and might either internalise their frustration (crying) or externalise it (get angry).
As they grow, they may become incredibly articulate but this might not be until later in life when other talents and potentials have blossomed. I was one who would cry, I just didn't speak much and unfortunately didn't have the help I needed, as females from my generation were simply marked as shy. One parent would be angry if I stuttered or couldn't get words out, the other was confused and so both compounded the issue. But it turns out Anomic aphasia is a genetic difference. Patience can move mountains, affording growth at its pace. My son has had his struggles, but because I was patient and helped him find the exact word, he became incredibly articulate early into his 20s. For me, it was late 30's and in the process of having parents who were clueless, I was fired from several jobs even though a 'hard worker', even when I tried to express dyslexia.
https://www.wikilectures.eu/w/Aphasia/PGS/diagnosis
Just posting to offer parents help :)