Yes, in most cases you can sell them together as one package, provided you have both a flight supplier and a hotel supplier connected to your portal and package selling is included in your plan. It is not something that works on its own, so it is worth confirming before you build your pricing around it.
When it is switched on, your customer searches once for a destination and dates and sees a combined price for the flight and the hotel together, rather than two separate results. They pay once, you send one invoice, and you can decide how much markup sits on the package as a whole instead of pricing each part by hand. For many agencies this is the main reason to sell packages, because a single combined price is harder for a customer to compare against an airline website.
What you should understand is that behind the scenes these are still two separate bookings with two separate suppliers, and each one keeps its own rules. The flight may be non refundable while the hotel still has free cancellation, so a change or a cancellation has to be handled part by part, and the refund your customer gets back will reflect whichever rules apply to each piece. If one of the two components sells out between searching and paying, the booking will not go through as a package and you will need to requote.
Also be aware that selling a flight and a hotel together can count as selling a holiday package under consumer rules in some countries, which brings extra obligations on you as the seller. Check with your own advisor on that point, and then ask us to confirm whether package search is available on your plan and with the suppliers you already have connected.