The 16f628 doesnt have ADC built in and its limited flash (2kW) might not be able to squeeze in the program for both a frequency counter and a mV meter. I suspect 16F88 is a better choice. If possible get a PIC with 12 bit ADC.
I am a new start in working with pic, so be indulgent
I had expected to analog inputs could be used as a voltmeter
Maybe I'm wrong, I want to measure AC picked up with a loop at the same time with a counter, but 2 separate function, and not at the same time, max voltage 5 volts
There are other ways to measure an analog parameter when you do not have a conventional analog-to-digital converter. All it takes is some imagination and creativity.
Since you already have a frequency counter, one way to measure voltage is to use a voltage-to-frequency converter.