5mm overjet. do you think this is signifying enough to get fixed? if so what is the best and most effective way to do so?!

Orthodontist: Dealing with excessive overbite/overjet is a complex issue that can have multiple treatment options depending on your particular case. Some cases can be treated by expanding the arches, some with extractions, and some just by alligning the teeth. You need to see an orthodontist for some study models, x-rays, and photographs to accurately diagnose & plan the best treatment option for you.

Your choice: 5 mm of overjet is more than ideal. Orthodontics may help if there is enough room to move your teeth into proper place. Jaw surgery many be required to fix if orthodontics alone will not help. Generally if the situation bothers you significantly then see a dentist/orthodontist to discuss your options. I see plenty of people with similar overjet measurements that get along fine.

Overjet: Horizontal overbite. Normal is 2mm. Yes, that's significant. Normally means there are other landmarks that are abnormal. 2 solutions. Best is have qualified Orthodontist resolve your Malocclusion. Or you can have your teeth reshaped, capped, veneered. Talk to both your General Dentist and an Orthodontic Specialist to help you to the best solution for you.