The Voigt profile is a model shape of spectral lines, i.e., a model spectral line profile. It is the shape the Voigt function is a convolution of two distribution functions, that model the result of two types of line broadening together, Doppler broadening and pressure broadening. (These, and the result, are termed line broadening functions, or broadening functions or BFs.) The math offers a means of analyzing a line regarding the two effects.
Given the challenge of convolutions, approximations have been developed, now probably most useful for cases where such a model's calculation must be done many times (or back-of-the-envelope analysis).