Here are some different ways to organize your workouts throughout the week. This is not an exhaustive list, but I think I cover all the basics.
First, know that you have options on how often you workout through the week. You can do anywhere from 1 day a week to 7 days a week (but it's advised to take at least 1 day off each week)
Second, you can choose to always do the same routines on the same days of the week or you can do them what's called asynchronously and do them in order but on whatever day of the week it falls on. Example: you have a routine that's 4 days long and you workout 5 days a week so you just cycle through them in order.
An example of a synchronous routine is that you always do the same workout on Mondays.
OK, now for the splits. Generally a workout routine is called a split because it splits up all your individual exercise between the days of the week.
The Bro Split
A classic. This split targets a particular muscle group or movement pattern each day of the week.
Example:
Monday: Chest / Tricep
Tuesday: Back / Bicep
Wednesday: Deadlift (Hinge)
Thursday: Shoulders
Friday: Squats (Quads)
Saturday: Running
PPL: Push Pull Legs
Very popular as of this writing. This split can be either 3 days a week or 6 days a week, usually it's a 3 day split. All exercises are placed into the 3 days based on essentially the name of each day. There's a day for all pushing exercise, all pulling exercises, and a day for legs.
PPL is kinda like a bro split but with less days in it. In the above example Monday is a push day, Tuesday is a pull day, Wednes day and Friday are both leg days, and the shoulders need to be mixed into the Push and/or Pull days
Upper/Lower
This split combines things even more than the PPL did and combines all upper body exercise into one day and all lower body exercise into another day. You could exercise twice a week, or keep rotating through for 2-4-6 days a week.
Arnold Split
My personal Favorite. Similar to a PPL but we're going to group things a little different
day1: Chest & Back
day2: Arms & Shoulders
day3: Legs
Full Body
This exercise split will focus on trying to do 1 exercise for each body part during every workout session.
Which is best? That's easy. All of them. There's no need to limit yourself. Try each one of them for 1-2 months each and see which ones you like or don't like. Then you can keep to your favorites after that. In the end the true best workout split is the one that keeps you actually enjoying your time working out and producing results for you.
How often should I workout? This one is a little harder. You need to find balance in your life. Do as much as you can consistently stick to. Do as much as you can recover from. If you workout so hard and so many days in a row that your body doesn't recover then you're actually going to lose muscle and strength rather than gain it.
Synchronous or Asynchronous? Do whichever you like. Myself, I very much prefer an asynchronous split since it allows me to take a day off whenever I need one either to rest or to just live my life. Then I just do the next workout on the list tomorrow.