If your spouse or de facto partner applies for an Australian visa, you can normally be included in that application as a member of their family unit. Some visas do not allow this, requiring that each person qualify for it on their own merit (working holiday visas, tourist visas, etc).
If your spouse or de facto partner already holds an Australian Visa, you may be eligible to be added to it. Each visa subclass has a rule determining if this is possible. Contact us for advice.