To expand a logarithm with multiple variables using SymPy, you can use the expand_log function. This function takes in the logarithmic expression as an argument and expands it by applying the properties of logarithms.For example, if you have a logarithmic expression like log(x*y), you can use the expand_log function to expand it into log(x) + log(y). Similarly, if you have a more complex expression like log(x**2*y), you can also expand it using the expand_log function.