How to tell if an equation is acidic or basic?

Chemical equations are neither acidic nor basic, but you can evaluate the products of the reaction (and maybe the reactants too) and identify the existence of acids or bases which will indicate what kind of effects the reaction will have on the acidity. However, I'm not sure if you're asking the question you want to know the answer to, maybe you're wondering about balancing redox equations (which you do differently in acidic vs basic environments), in which case you'll need additional information beyond just an equation, but if the equation is redox and it's balanced just look for the presence of H + ions or OH - ions on either side and that will tell you if it is acidic or basic (respectively), if neither is present, it'll be neutral.