Someone tell me about this game in a concise manner, please.
Fabula Ultima is a TTRPG inspired by Japanese Roleplaying Games, particularly Japanese console games (e.g., Final Fantasy, Chrono Trigger, Dragon Quest, Octopath Traveler, Zelda, etc.) and inevitably also some anime. It's meant to emulate the feel of these games as a whole.
The game draws inspiration as well from narrative-first games like PbtA games, Blades in the Dark, Fate, etc. but also games like 13th Age and 4e D&D.
The resolution system is adopted from the Japanese "tabletalk game" Ryuutama. It involves having four attributes that are rated by different die sizes. Most checks involve rolling two dice based on the two (or even one) attributes involved plus modifiers (weapons, spells, etc.) vs. the Difficulty set by the GM.
The game also uses Fate-like aspects for characters (Traits) as well as character Bonds (with a PC/NPC, nation, organization, etc.). There are Fate-like points for PCs called Fabula points. Likewise the GM has Ultima points that can be used for villain actions: e.g., having them escape after being defeated, invoking traits, recover, etc. The GM can also escalate by powering up the villain.
All characters are multiclass characters, typically combining 2-3 class/job options to a max cap of 10 levels per class. Starting characters actually start at level 5 and there are 50 total levels. When you level in a class, you are typically either gaining a new ability (e.g., spell, talent, invention, etc.) or improving one (to the cap).
Edit: Here is a Character Sheet from the Press Start quickstart so you can get a bird's eye view: