What does it mean if an AC motor has two voltage ratings?
(Assuming you are talking about an induction motor)
Such a motor will have six terminals - i.e. start and end points of all three windings available, which you should connect as star or delta. The terminals are arranged to allow you to do this easily.

The motor is rated to tolerate 230V RMS across points U1-W1, U2-W2 and U3-W3. If you connect it in
in star connection you can have V(L1-L3) = 230*sqrt(3) = 400V rms.

In delta mode you can only have V(L1-L3)=230V, so you probably shouldn't
directly connect it to the 440V 3-phase supply in delta mode.