Practically speaking, this means that a table need not contain all of the raw data from your research or complicated statistical breakdowns.
It should include enough, however, that a reader can see any trends apparent in the data, especially those highlighted in the text.
An appendix contains supplementary material that is not an essential part of the text itself but which may be helpful in providing a more comprehensive understanding of the research problem or it is information that is too cumbersome to be included in the body of the paper.
A separate appendix should be used for each distinct topic or set of data and always have a title descriptive of its contents.
It should replace a lot of text and explanation, making the results and discussion part of the paper shorter and more clear, although it must be referred to in the text, rather than left to stand alone.
The simple answer to this is a much as is needs and not more than is necessary!
The only other distinction is that you should number tables in the appendix separately, as Table A1, Table A2, to prevent confusion.
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Appendices are always supplementary to the research paper.
As such, your study must be able to stand alone without the appendices, and the paper must contain all information including tables, diagrams, and results necessary to understand the research problem.