en_tn_condensed/isa/62/06.md

I have put

Here "I" may refer to Isaiah or to Yahweh.

watchmen on your walls

This refers to prophets, officials, or possibly angels, who are constantly praying for the people of Jerusalem like watchmen who constantly guard the city.

they are not silent day or night

"they are earnestly praying to Yahweh throughout the entire day"