what is the meaning of X[i,] in python

Question

I am a beginner in python

I have encountered this particular notation in python on a kaggle kernel.

I understand what X[i,j] or X[i] means, however i cannot understand what X[i,] means.

link to the kernel: https://www.kaggle.com/meaninglesslives/nested-unet-with-efficientnet-encoder

code snippet:

X = np.empty((len(list_IDs_im),self.img_size,self.img_size, self.n_channels))

X[i,] = cv2.resize(im,(self.img_size,self.img_size))

This was a computer vision problem