This method keyword requests a Local Spin Density Approximation calculation, using the Slater exchange functional and the VWN correlation functional for the DFT calculation. It is equivalent to SVWN. Note that LSDA is not uniquely defined in the literature. In fact, many differing but related methods are referred to using this term. Other programs offering an LSDA method may use somewhat different functionals. For example, some implement the functional specified by the SVWN5 keyword, while others use a correlation functional of Perdew. While Gaussian offers this keyword for convenience, it is probably better practice to specify the exact functional desired; see DFT Methods for full details on specifying and using Density Functional Methods in Gaussian.
