what isthe meaning of angular momentum of electron.?

Schrodinger Equation

The "angular momentum" quantum number l = 0, 1, 2, ... determines the magnitude of the angular momentum. The "magnetic" quantum number m = −l, .., +l determines the projection of the angular momentum on the (arbitrarily chosen) z-axis.

Only the hydrogen atom which has only one electron cam be computed exactly. All other calculations are statistical approximations.

Spherical harmonics are the angular portion of an orthogonal set of solutions to Laplace's equation represented in a system of spherical coordinates. Spherical harmonics are important in many theoretical and practical applications, particularly the computation of atomic electron configurations.

It is part of the solution to the relativisitic Schrodinger equation derived by Dirac.

The angular momentum of an electron (and really it's just a macroscopic description of a microscopic phenomenon) means the electron seems to be spinning in an axis, similar to the Earth spinning on its axis.

This momentum has a value of "1/2", which is interesting unto itself b/c in the original Schrodinger the solutions should be integers.

The 1/2 spin means the electron induces a small magnetic moment, which is the explanation for the high magnetic permeability of materials w/ lots of unpaired electrons, like elemental iron (ferromagnetism)

And it also means that in the presence of an external magnetic field, the electron's field can align w/ that field (low energy) or be anti-parallel to it (high energy). This is the basis for Zeeman splitting/spectroscopy, and is similar to the effect in NMR and MRI.

it's part of the schrodinger equation which can't be solved if you have more than one electron