what parameter estimates are returned by the maximum likelihood function mle() ?

I have a basic question that what parameter estimates are returned by the maximum likelihood function mle() ? are these 'Mean' and 'Standard deviation' or 'Mean' and 'Variance' ?

For example: phat = mle(data) returns maximum likelihood estimates (MLEs) for the parameters of a normal distribution, using the sample data in the vector data. So what will be the other parameter along with the 'Mean'? Would it be 'Variance' or Standard deviation' ?

Sorry for my lack of knowledge in statistics. Thanks in advance.