How is Harriet Tubman singing the forbidden spiritual symbolizing to the enslaved people to whom Harriet Tubman is signaling

She was using these spiritual songs to convey messages to the enslaved

Explanation:

During their enslavement, harriet tubman and the enslaved people used spiritual songs as secret languages for sharing informations amongst themselves.

During their escape to the north through the underground railroad,codes were used in the songs they sang as a means of communication without the slave owners being aware. So tubman used these spirituals as code to tell her fellow slaves of her plans.