Learn Portuguese (Portugal): O fornecedor, cuja loja conhecemos, vai expedir a caixa dentro de um mês. - The supplier, whose store we know, will dispatch the box within a month.

Both phrases talk about the future, but they mean slightly different things. Dentro de um mês means the box will be dispatched sometime within the next month (it could happen tomorrow, next week, or on the last day). If the sentence used daqui a um mês, it would mean the dispatch would happen exactly one month from today.

Why is it cuja and not cujo, since the supplier (o fornecedor) is masculine?

The word for whose (cujo) is special because it changes to match the gender and number of the thing being owned, not the owner. Since the store (a loja) is feminine and singular, we use cuja. If we were talking about his cars (os carros), it would be cujos carros, even though the supplier is a single masculine entity.

Is expedir the standard word to use for sending something?

Expedir specifically means to dispatch, forward, or ship goods, making it perfect for a formal or business context like dealing with a supplier (um fornecedor). For everyday situations, like sending a letter or a birthday gift to a friend, you would usually just use enviar or mandar.

Could conhecemos also mean we met in the past?