The cobweb, because it is easily damaged, signifies indecision, perhaps an idea that has not quite crystallized yet.
On a purely practical level the cobweb symbolizes unused talents and potential which has been allowed to go stale.
The evidence of timely entrapment, and a warning to beware; see “spider”
If there is no spider in the web, it indicates calm days and happy times ahead. If you see a web being spun, you’re in soon for some criticism.