If you are prepared to work hard, learn and improve then this should not be an issue for you. Be punctual and care about your job.
If you are not absolutely clear by the end of your staff training about what your Director's expectations are of you, then just ask. This won't be perceived as a sign of weakness - it will show that you care about doing a good job.
If you were hired for a specific activity role at camp, ensure you have brushed up on your skills before you arrive at camp. Camps don't want lifeguards who've forgotten how to swim!