My Samoyed has a lump on its tail with something flesh-like inside. What is it and does it need surgery?

It is likely an insect or parasite bite, or a local wound infection. Insect bites cause swelling and itch; check the whole body and use antiparasitic medicine with wound care.

For wound infection, shave the area, clean with saline or hydrogen peroxide, disinfect with iodine, then apply erythromycin ointment to prevent secondary infection. Healing scabbing is good; if much discharge, see the vet for debridement.