To be honest, I'm really struggling with this one. In your sentence, "da" indicates something that will happen in the future. At least to me it does. Also, it feels right to use "bestimmt" whenever you have this kind of sentence. Both are equivalent in meaning for me: > Super, sie wird sich (bestimmt) freuen. > Super, da wird sie sich (bestimmt) freuen. I thought about it for a long time but couldn't find a proper 1-word translation. Also I figured the sentence can be in the past as well. > Super, da hat sie sich (bestimmt) gefreut. Again, "bestimmt" wants to be in the sentence. So I concluded, the sentence is used whenever you talk about something you don't see, something that is happening somewhere else. Thus you say "da" = "there" to point at the event and "bestimmt" because you make an assumption. While "there" is used for locations, "da" can be referring to both place and time. The best I could do was: "da" = there/then

Hm, I know you perfectly understand German. But this way I don't get off track. With the explanation of this being a reaction to the fact that you are going to pick up that girl: she will be happy about it So in this context you can see "da" as a short form of "darüber", just like Alexandre explained. We also use quite often this version: dann wird sie sich freuen. Which would get us to Jahn's then. But I would not think that this applies in this context.

I assume you want it translated to English?