Particularly during the Spring and Summer months when your garden plants seem to grow at one cm per second it’s easy for central heating boiler and other flues to become blocked, creating a risk from carbon monoxide gases which cannot be properly vented to the outside.
Do take the trouble to walk around the exterior of your home from time to time to check on possible problems such as that identified in the photograph. Yes, there is a flue in there somewhere.
Cut the vegetation back, or ask someone to do it for you. It could be one of the most important pruning jobs you ever undertake.