Working day means business day. If you are lucky it will arrive on Friday. If not, then Monday.
In your case it means monday to friday. So Sat and Sun do not count as working days.
In other cases it might also express the amount of work in one day towards a goal, for example 8 hours a day. Then 2 working days would be 16 hours of labor by one person or 4 hours of work by four persons.
Your packet should be there Friday or perhaps Monday if the posting or delivery will delay.
Be well.
If you're lucky & the post is running well, you could receive your order tomorrow morning, Friday.
But chances are you may not receive it until Monday, the next working day after Friday.
9am to 5pm Monday thu Friday Weekends are not working days
What Is one working day? ?
I placed an order at 8:30AM on a Thursday the website said it will take one working day, when will my package arrive ?
