In brief
grid-row determines an item's row span in the usual horizontal writing mode. For example, span 2 can extend it across two rows.
Useful to know
grid-row determines an item's row span in the usual horizontal writing mode. For example, span 2 can extend it across two rows. [1]
This affects spaces available to automatically placed neighbours. In a grid with a large lead card, inspect its span together with the remaining items' sequence and the available row sizes.
Sources
For further detail and to check the information: