Use an anvil
Place the damaged tool in one anvil slot
Place the same tool type or matching material in the other slot
Combine two damaged tools to repair durability
Use the same tool and a material like iron ingots, diamonds, gold ingots, or netherite ingots depending on the tool
Use the grindstone to remove enchantments and repair by combining two damaged items of the same type
Use the crafting grid to combine two unenchanted tools of the same type
Use the Mending enchantment and gain experience to repair the tool while holding or wearing it
Use a smithing table for netherite upgrades, not for normal repairs