Net carbs are what count on keto. Take the total carbohydrate from the label and subtract the fibre and sugar alcohols your body does not absorb. More on the why in net carbs explained.
Net carbs = total carbohydrate − fibre − sugar alcohols. Fibre and most sugar alcohols (erythritol, allulose) pass through without raising blood sugar, so they come off in full. Maltitol is the exception: it is partly absorbed and does spike blood sugar, so the common convention is to subtract only half of it. On labels using the American convention, fibre is already outside the "total carbs" figure, so check whether your label is EU (fibre included) or US style. This is a guide, test your own response if you are unsure.