It currently isn’t possible to embed just a single block on a website. You can embed an entire base and choose to show the blocks in the base. However, that may reveal more information than you want.
Some people on this community have found references to a beta for embedding a single block, but it is not mentioned on the Airtable support website.
You also might want to look into the issue in this topic, to see if you are experiencing the same results.
If this answers your question, please mark this post as the solution. Otherwise, could you please give a bit more details and a screen capture?