In Rambam's negative theology, there is a distinction between descriptions of G-d's essence (which we can only speak about in negative terms, e.g. G-d is not physical, non temporal, non ignorant, etc.), and attributes of action. The attributes of action are "those that do not describe G-d directly, [but] rather His interaction with creation" (per this wiki entry). Some examples of attributes of action are that G-d is merciful, that G-d is mighty, that G-d is a redeemer, etc.
But don't the attributes of action, in fact, also describe G-d's essence? For example saying that G-d is mighty can be interpreted to mean that certain events caused by G-d (like the Exodus) happened in a way/fashion that we humans would ordinarily call "mighty", in the ordinary sense of the word. But we're then also saying that it was G-d who was "mighty" - i.e. those events didn't just happen by themselves, they were caused by G-d, who performed them in a mighty fashion. So then here we have an attribute of G-d's essence, namely that He is or has-the-property-of-being "someone who performs certain events in a certain (in this case, mighty) fashion".
So how is this knowledge of G-d (i.e. the knowledge of certain properties of physical observable events that are attributed to His actions) really different from any other statement about G-d or His essence? According to negative theology, we can't say that G-d exists in space, for example, because G-d is utterly indescribable. And yet, we can say something specific about the way He operates and interacts with the world? If he is utterly indescribable, we should not be able to know anything at all about Him, including any knowledge/properties/restrictions/specifications of His interactions with the world!