An empty statement is any statement
that is purported to provide information, but in reality it provides no
information at all in the relevant conversational context.
In ordinary situations, tautologies or tautological statements are all empty. A tautology is a statement that is true in virtue of the meaning of the logical connectives present in the statement. These connectives are connectives like "not", "and", "or", "if ... then ...", "there is", "every", "none" and the like.
For example, suppose Helen asks whether Francine will come to the party, and Francine replies, "If I come, I will come." This is a tautology as it is necessarily true given the meaning of "if then". But the statement provides no information as to whether Francine will attend the party. So it is indeed an empty statement.
Similarly, the statement that "either it will rain tomorrow, or it will not" is also a tautology. Obviously, if we want to communicate information, we should avoid using tautologies as they provide no useful information about the world. This is not to say that they are completely useless. Tautologies can be useful in logic, and sometimes they serve as reminders about available courses of actions (e.g. "Either we get married, or we don't").
A tautology is a special case of what we might call analytic statements. These are statements that are true solely in virtue of their meaning. Here are some examples:
If a competent English speaker asks whether Tom is a bachelor, and you answer, "a bachelor is an unmarried man", then your statement can be regarded as an empty statement. Although your statement is necessarily true, it offers no information relevant to the enquiry. On the other hand, if a student is learning English and is wondering what a bachelor is, then your answer does provide some useful information, so in such a case we should not say that the answer is empty.
If we want to communicate information clearly and precisely, then of course we should avoid empty statements. On the other hand, there might be occasions where we want to be evasive and non-commital. In such situations, empty statements might be very useful indeed.
I carry my thoughts about with me for a long time, often for a very long time, before writing them down.

Ludwig van Beethoven