I am not qualified to give advice (purely based on experience) Growing up, I knew I sometimes had trouble saying what I wanted to say but I didn’t have a name for it until I got older. Eventually I learned what a stutter is and started telling people I had one — I was right. Seven is young. You know him best, if he’s chatting away, maybe the best approach is to frame it like “sometimes it feels like the words I’m trying to say get stuck and I have trouble saying them, have you ever felt this way?” and then (if yes) some variation of “okay, let’s practice how to get them unstuck together” or “okay, when I feel words about to get stuck I (insert strategy here) and it sometimes helps”. While you may not stutter, kids usually think anything their parent does is normal. Keep in mind, he probably stutters most around you and he’s growing (the stutter will ebb and flow he grows).