The answer to this question depends on the size of the tumor, the location of the tumor, the type of tumor, and the depth of the tumor. It sounds like you have a small growth on your shoulder that needs removed. Most surgeries such as this one are day surgeries and you will be able to go home the same day. The incision will be small and blood loss minimal. You will probably be sore for a few days but will likely be back to full activity within a few weeks at the most. This is especially true if this tumor is a growth from your skin (such as a large mole). If this is the case, you will be back in full swing within several days.
The key exception to this rule is if the tumor they are removing ends up being a sarcoma. Sarcomas are cancers of the muscle, bone, or other soft tissue cells. These cancers require a large incision and a large amount of tissue removed in hopes for a cure. In addition lymph nodes in the area may need removed. Recovery from these types of operations are longer. While your situation does not sound like this, I did want to give you an example of an invasive oncology surgery
I suggest that you schedule an appointment with your surgeon
before the day of the operation. Ask what type of tumor you have, and what type of surgery this is going to be. This way you will know what the recovery period will likely be.