You will need different sizes of hooks to suit the different baits and species of fish you are intending to catch.
There are many kinds of hooks made in different gauges of wire, both with and without eyes, with and without barbs, and available loose for tying yourself, or already attached to line.
Hook sizes are described using a numerical scale, the higher the number meaning the smaller the hook. This is variable, though, and different manufacturers seem to apply their own rules about how big a hook should be for a given size.
Over time you will find that you need specialised hooks to suit the types of fishing that you do. For now, though, a few sizes and styles will be versatile enough to cover the various fishing situations you encounter, and a range of hooks of sizes 20, 18, 16, 14, 12, 10 and and 8 will be enough to get you started.
Barbless hooks are better when you are starting out learning to handle fishing equipment competently as they are easier to remove from nets and clothing than barbed ones. If you start a session using barbless hooks and find that the conditions are causing you to lose fish, you can always change to a barbed hook and see if that improves things.
Initially the pattern of hook you choose is not too important and a range described as general purpose medium wire hooks will be versatile enough to cover most of your fishing.
By all means buy hooks already tied to line if you prefer and can afford it, but for maximum flexibility loose hooks are better as you can then tie them to various strengths of line.
Loose hooks are available both with eyes, and with ‘spade’ ends. The former can be tied quite easily by hand, whilst the latter are best tied using a tying aid, usually described as a ‘Matchman’s hook tyer’. Eyed hooks, or those already attached to line may suit you best, as you may feel that you have enough to learn and master already without having to learn to use a hook tying device.