They are palpal bulbs
The swollen ends of a mature male's pedipalps are reproductive structures and confirm that the male has reached maturity.
They appear after a maturation moult
A juvenile male does not have the adult bulbs. They become obvious after the moult that brings the male to maturity.
Why they are called boxing gloves
From above, the enlarged pedipalp tips can look like tiny gloves held in front of the spider. The nickname is memorable but the structures are not used for fighting.
Use them to explain behaviour changes
Once the bulbs appear, roaming and reduced appetite become easier to interpret as mature-male behaviour rather than an enclosure problem.
Handling is not needed
You do not need to pick up the spider to inspect them. Good lighting and a view through the enclosure are normally enough.
Photograph and record
A clear photograph and the maturation-moult date are useful collection records, especially if the scientific name or identification later changes.