The Sun and other planets such as Neptune, Uranus, Jupiter, and Saturn are 'gas -giants' and their rotational speed is influenced by a phenomenon called Differential Rotation. This means that the rotational speeds vary at different regions of the celestial object. The prime factors causing such behavior include the object's composition, its magnetic field, and the convective currents. Convective currents are basically the movement of a fluid from an area of high density to an area of low density. This, thus forms areas of high and low density. The equatorial regions of these celestial bodies experience a more rapid rotation mainly due to these convective currents, present in the outer layers. These convective currents transport heat from the interior to the surface, and the Coriolis effect, resulting from the rotation, causes the gas to move in a swirling motion. This motion amplifies the rotation near the equator, leading to faster speeds compared to the polar regions.
Although this is an incomplete explanation of this topic since convective current can be complex in 'gas giants', but I think it will suffice. Hope it helps!