You need to compare it with the expected value or with values at other locations. But it shows the difference in composition of species between locations or sites. It is negatively related to number of species

Andrew Paul McKenzie Pegman Thank you very much

You're welcome :)

You can easily count several β‐diversity indices whit PAST software: https://folk.uio.no/ohammer/past/index_old.html (this is the old version, but it is enogh and easy to use.) The software has a good manual!

Diversity menu/Beta diversity... for example Whitaker index

Gyula Kovacs Thank u. Yes the mentoined value came from PAST3. I only need some explanation about it. Is there any range value for Whittaker like Shannon and Simpson?

How many samples (plots) do you have? If you have two samples, then global

β diversity and pairwise comparison are the same. If you have more samples, then you get a result for global β diversity and for each pairwise comparisons. But this β diversity only applies to presence-absence data (see PAST manual). If you want to take abundance into account, you should use the Bray-Curtis index (see PAST manual).

Gyula Kovacs only two samples. Thanks for your suggestion.