Non-US practitioners, particularly in Europe, almost always use "and/or" language in the claims for numerous reasons (worries about original disclosure, future amendments, examination procedure, excess claim fees, etc.). The meaning of this term cannot really be questioned - it means one option could be "A and B" and another option could be "A or B."
In the US, examiners generally disfavor this term, although it is not exactly clear why. Examiners often reject "and/or" in the claims as indefinite under Section 112. However, as noted above, it should be clear that there is nothing inherently indefinite about the term. Because some examiners are insistent on maintaining rejections of this term, it might be helpful to see what the PTAB says about it.
The PTAB has actually confirmed that there is nothing inherently wrong with "and/or" numerous times, including in ex parte Gross. The Board's analysis is hardly earth shattering. It simply states the obvious in one sentence.
While this result seems quite normal, it is notable given the related problems with (and seemingly backward interpretations of) the terms "and", "or", by themselves, as well as in situations such as "at least one or more of A and B." The courts and PTAB have twisted the meaning of such terms to mean the exact opposite of what one might think. Consider the recent PTAB decision in ex parte Jung (note that the USPTO just recently withdrew the "informative" designation of Jung).
So, in a sense, perhaps the clearest and safest choice is to turn back to "and/or". While examiners may disfavor it, the approach is well accepted in foreign jurisdictions and has been confirmed to be just fine by the PTAB. Plus you never have to worry that "and" will mean "or" or vice versa, since you have them both.