vstrImages.push_back(strImagePath + "/" + ss.str() + ".png");

This line of code is written in C++ and is used to add an image file path to a vector of strings.

Explanation:

- vstrImages is a vector of strings that stores file paths of image files.
- push_back() is a function that adds a new element to the end of the vector.
- strImagePath is a string variable that contains the path of the directory where the image files are stored.
- "/" is a forward slash used to concatenate the path with the file name.
- ss is a stringstream object that is used to convert a number to a string.
- ss.str() is a function that returns the string representation of the number stored in the stringstream object.
- ".png" is a file extension that indicates the format of the image file.

Overall, this line of code adds a new image file path to the vector of strings by concatenating the directory path, the image file name (represented as a number), and the file extension.