The foreskin has protective, sensory, biomechanical, and immunological functions. Throughout life, the outer part of the foreskin protects the sensitive inner part of the glans from injury, abrasion, chafing, and infection. The foreskin keeps its mucosal tissue and the glans soft and moist so that it maintains sensitivity. However having a circumcision eliminates the risk of phimosis and balanitis, conditions which often come with pain, particularly during urination and sex.
The foreskin also secretes immunological substances that fight infection, called lysozymes, and also produces natural lubricants, reducing the need for artificial lubricants during sex. Once you have had a male circumcision, you may find that you will occasionally need to use extra lubrication.
A foreskin has no role to play in reproduction, so having circumcision will not affect your sperm production or fertility.