I think i know what you're asking about the specializations, so let me break this down for you. When you're first starting out you've got three main paths to choose from and each one's gonna shape how your character develops

Combat's probably the most straightforward, giving you skills like blade, blunt, hand-to-hand, armorer, block, heavy armor, and athletics. Something interesting to note is that focusing here makes you naturally tougher and lets you progress faster with weapons and armor which is really helpful early on

Magic users get access to destruction, restoration, alteration, conjuration, mysticism, illusion, and alchemy. The cool thing about going this route is you'll get better at casting spells more quickly, and they'll cost less magicka to use. A lot of people don't realize that mysticism actually makes all your magic more effective not just the obvious stuff

For the sneaky types, you're looking at sneak, security, marksman, light armor, acrobatics, mercantile, and speechcraft. Good to know that athletics actually belongs to combat even though it might seem like a stealth skill at first glance. Going this route means you'll get better at all the subtle arts like lockpicking and moving quietly plus you'll naturally progress faster in these skills

The best part is that no matter which path you choose, you'll get a nice +5 bonus to those related skills right from the start. Just remember that while these specializations give you a head start in certain areas, they don't lock you into any particular playstyle you can still develop any skills you want later on