I would ask the school about his speech. If he's in public school maybe they could do a speech evaluation to see where they are.
Five year old boys are VERY immature. His social skills may be behind too.
Hi. Well a couple of things. First let me tell you that it is not uncommon for a 5 year old to not recall or tell a parent what happened at school. This is something you hear over and over. They get tired, they don't feel like discussing it and as we parents that care about them and are interested in them want to know everything they do when they aren't with us . .. we get a little frustrated when they say they don't know. We had this just last night with my own 5 year old at dinner when my husband asked him what he did in school. Ugh, to be honest . . . my 7 year old was super tired last night and wasn't coming up with anything either. Quiet night at the dinner table! My point is, that this is not uncommon.
Now speech is a different story. If you are around other kids his age and notice they are advanced past where he is, this is a red flag. All kids are different but speech issues usually show themselves as compared to what is within normal. So, is your child outside of what other kids his age are doing? And having issues with speech hinders social interaction/friend making because you count on speech to interact. So it makes sense that he has difficulty with friends if he has difficulty with speech.
There are three parts of speech-------- expressive (how he organizes and puts thoughts together that he himself speaks), receptive (how he organizes and puts thoughts together that others speak to him, how he processes it) and articulation (actually saying the words). All three areas are important to speech. If you have a concern, I'd advice seeing a speech specialist and have him assessed. Many kids with some work with a speech therapist overcome any issue.
There is also a part of the processing system/nervous system called motor planning which can involve any of the three parts of speech. If there is an issue with motor planning, a child will have trouble with any or all of his speech. I'd think that if this was the case, you'd also see issues with fine motor skills as well such as writing or using scissors.
Consider the speech evaluation just to make sure your son doesn't need any extra help. And what you can do for social skills is set up some one on one play dates with children from his school. You stay active in the play date as 5 year olds still like to play with the moms and help him out. This will help him learn interaction that is appropriate and build his confidence. good luck (oh, and volunteer at his school as much as possible)