Definition of Polish Topology

Question

Let $\xi$ such that $1 \leq \xi < \omega_1$ and $f$ be of Baire class $\xi$. In this paper (Section $5$), the author defined

$$T_{f,\xi}=\left\{ \tau^{\prime} : \tau \subset \tau^{\prime} \text{ Polish}, \tau^{\prime} \subset \sum_{\xi}^0{(\tau)}, f \in B_1(\tau^{\prime}) \right\}$$

I don't understand the meaning of Polish topology. I search online and but I couldn't find anything about it. What I found is Polish space but not polish topology.

Answer 1

I would say that it is a topology (on the presumably fixed underlying set), that makes it a Polish space (i.e. separable and completely metrisable).