I believe the lump is smegma.
Smegma is a natural, normal, harmless, and healthy substance. It is a mixture of exfoliated skin and skin oils. Smegma collects under the foreskin. It is normally white in color.
It can get irritating if it stays for a long time without being washed away, so it is good practice to wash under the foreskin periodically.
Accumulated smegma may get hardened and difficult to remove if it stays a long time such as under a foreskin that is not retracted. Olive oil has been recommended for softening and removing hardened smegma.
Baby boys are born with the inner layer of the foreskin fused with the surface of the underlying glans penis. This is natural, normal, and protects against infection. Over some years the fusion spontaneously disintegrates and releases the inner foreskin. This usually happens prior to puberty, but not always.
Apparently, your foreskin has not yet released. You can try peeling the foreskin away from the glans penis to see if you can break the remaining fusion. Do it carefully and little by little. It may take you several tries to get it all.
When you tear the foreskin away, the head will be red in color, where the separation occurred, for a while. Put some Vaseline under your foreskin to prevent it from re-adhering to the head.
If you can’t get it to separate by pulling on it, a urologist can help you. It is called “lysing”.