What's the early stage of syphilis?

Primary Stage
During the first (primary) stage of syphilis, you may notice a single sore or multiple sores. The sore is the location where syphilis entered your body. Sores are usually (but not always) firm, round, and painless. Because the sore is painless, it can easily go unnoticed. The sore usually lasts 3 to 6 weeks and heals regardless of whether or not you receive treatment. Even after the sore goes away, you must still receive treatment. This will stop your infection from moving to the secondary stage.

Source: U.S. Department of Health & Human Services