Can someone explain to me the concept of this game? Will all I do is track and kill monsters?
You'll be spending the majority of your time tracking and hunting monsters, but there are other types of quests. Some will require you to capture (not kill) one or more monsters, others to gather resources (which includes mining, fishing, and hunting or capturing smaller creatures) and even steal items from bigger monsters (whelps, eggs, or something valuable they're protecting).
And it's all about crafting better weapons and equipment so you can take on bigger and stronger monsters, and combining materials to make better or more useful items. This was removed from the beta, and it's one of the best parts of the game!
You also have access to a farm. Earlier entries in the series let the player do most of the grunt work and even upgrade certain gathering spots with gameplay elements similar to farm simulation games, although in recent years, it's been stripped down to basically nothing, a mini-game or a list of options given by an NPC, so I wouldn't expect too much.
I honestly felt overwhelmed with all the options right off the start
I've been a MH player since the PS2 and PSP days, and the beta was overwhelming even for me! This is because they give you a ton of items so you can try them out, but you normally start with literally nothing and get most of those items when you're somewhat far into the game. In reality, you would only bring the items that are absolutely necessary for a quest and leave a lot of space in your inventory.