Step 1: Harvest and process grains (heating and drying, plus cracking).
Step 2: Steep the processed grains in hot water to make wort (a sticky, sugary mash).
Step 3: Boil the wort while adding hops and spices.
Step 4: Cool, strain, and filter the wort, then pour it into a fermentation vessel. Add yeast.
Step 5: Age and bottle.
That's a hyper-simplified explanation. For alcohol, we have yeast to thank: the bacteria eat the sugar in the wort and releases CO2 and EtOH (alcohol) as byproducts.