I need to print two side but it’s gray out on my hp laser jet pro mfp m477fnw

Hp color LaserJet Pro m477fnw do not offer any duplex features and cannot perform such duplex printing automatically. However you may manually perform duplex printing with your printer model, not automatic. To manually print on both sides, the feature is only available if you install the HP print driver. Click the File menu, and then click the Print option. In the Printer menu, select your printer from the list. Open the menu drop-down list or click Show Details, and then click the Manual Duplex menu. Click the Manual Duplex box, and then select a binding option. Click the Print button. The product will print the first side of all the pages in the document first. It might not be available if you are using Airprint.