Please Help ME!

- What are Fit indices? are they similar to R squared in regression? For example chi square and RMSEA are the 2 most popular...how are these calculated and what do they represent?

- If a model with 5 variables is created on AMOS... what do these fit indices mean? a book says software compares observed covariances with predicted covariances...What does this in simple terms mean?

Best Regards,

Sam