As is the case with many a legal question, the answer is “Maybe.”
You may appeal as a matter of right on foreclosure judgments. That means that the Court of Appeals will definitely hear your appeal (in other cases, you have to ask permission to appeal, but not in the case of foreclosure judgments).
However, pursuant to 808.07(1) and 808.075(1), Wis. Stats., this does not automatically stay the execution of a judgment. In the foreclosure context, the Sheriff Sale is an execution of that judgment. This means that anytime after the court-ordered redemption period has passed, the bank can hold a Sheriff Sale, even if you are mid-appeal.
However, you may ask the Circuit Court, pursuant to Wis. Stat. 808.07(2), to stay the execution of the foreclosure judgment in your case pending your appeal. Whether or not this will be successful is within the discretion of the trial court. Essentially, if the trial court thinks you have a viable legal issue and finds you sympathetic, then it will probably grant a stay on execution, effectively delaying the Sheriff Sale. If the judge commented on how there is a legal issue involved that the Court of Appeals should resolve, for instance, then the Court will be more inclined to grant the stay. However, if the Court thinks you are just delaying the matter for the sake of delay, or if it thinks your appeal has no merit, then it will probably deny your request to delay the Sheriff Sale.