Start with serving size. Café nutrition is usually listed per drink size, and a venti can be listed as a single serving even though it holds 24 ounces. Every other number follows from that choice, so check the size before comparing drinks.
Calories tell you the total energy; sugar tells you how much of it arrives fast. Two drinks can both be 200 calories while one carries 10 grams of sugar and the other 40 — the second will feel very different by mid-afternoon. Caffeine is listed in milligrams: a grande brewed coffee is roughly 310 mg, a double espresso about 150 mg, and most adults are advised to stay near 400 mg a day.
Protein and fat mostly track the milk. A latte's 10–13 grams of protein is simply the milk's contribution, which is also why swapping to almond milk cuts protein along with calories. Read together — size, sugar, caffeine, then everything else — the label stops being noise and becomes a quick decision tool.