To home in on something means to get closer to a target. The phrase comes from homing pigeons who are able to find their way home from a great distance. The people who first designed guided missiles saw the similarity between the missiles and pigeons and began to use home in on a target when talking about missiles too. Now English speakers can use the phrase for many things, like, for example, tables at a farmer's market.
I guess that he is uncertain that this table is his actual target. What is he looking for?