If the replacement motor has the same color/quanity wires then reconnect to make sound electrical connections. If the wires on new motor are different, then this is the rule of thumb: the white motor lead is neutral - usually connects to the white from the panel, green is ground - usually connects via an eyelet from a ground to a bare copper, and the black/blue/red are the speed windings from high to low on a multi-speed motor. The hot wire (usually a black coming from a circuit breaker) going to one of the colored leads is very likely to be switched and/or an in-line speed control could be installed at this point.
If this is new installation, the electrician will bring in the correct power wires and prep the installation to be to code. If you are left with wiring the motor from that point on then refer above for which motor leads to connect to what.