What is Radial and angular parts?

In spherical coordinates $(r, \theta, \varphi)$ about the nucleus, the orbitals of a hydrogen-like atom factorise as $\psi_{nlm}(r, \theta, \varphi) = R_{nl}(r)\, Y_{lm}(\theta, \varphi)$: the radial part $R_{nl}$ depends on $n$ and $l$, the angular part $Y_{lm}$ on $l$ and $m_l$ only.