Welcome!

Adding onto what Taika has mentioned, once you join a Grand Company as part of the story and start gaining Company Seals during FATEs, you'll be able to purchase a consumable item from the GC's shop called 'The Keeper's Hymn', which allows you to completely reset a class/Job's spent attribute points, meaning you can then reassign them if you feel you put them into the wrong stats.

They disappear upon use, but you can buy more Hymns so you can reset your stats whenever you wish as many times as you wish (assuming you have enough seals to buy it of course).