Mods like Just Enough Resources, JEI, JEED and more offer info on any block, item, effect or mob you want to look up.
The AppleSkin mod adds tooltip information to all the foods so you can tell how much hunger and saturation you'll receive. You'll also get a preview in your HUD of the hunger and health a food can restore while you're holding a food item.
Thanks to Apathy Mod, easy difficulty has been changed so monsters won't attack unless you attack them first. And the Jade mod displays info about whatever you target at the top of the HUD.
The Lexicon mod adds an intuitive guidebook that explains every feature of the game.
The advancement screen is bigger and easier to navigate thanks to Better Advancements. And Clickable Advancements allows you to jump to the screen quickly when an advancement pops up in chat.
The Tips mod provides handy snippets of info during the loading screen and when you have your inventory open.