No one can really offer an opinion concerning whether the proposed non-solicitation agreement you describe is enforceable or, if so, what limits it will place on you without reading the agreement and discussing it with you.
That said, generally agreements not to solicit an employer's accounts for a period of time after the termination of employment are probably enforceable provided they aren't essentially non-competition agreements which have certain statutory conditions and limits to enforcement. If you have concerns you should invest some time and money to hire an attorney who can help you.
The statement above does not create an attorney-client relationship. This response should be considered general legal education and is intended to provide general information about the question asked. The question often does not include important facts that could significantly change the response. Information provided here should not be used as a substitute for legal advice from a licensed attorney that practices in the subject area in your state. The law frequently changes and can greatly vary from state to state.