In this verse, God is providing Moses with a third sign to convince the Israelites and Pharaoh of His divine authority and the legitimacy of Moses' mission. The transformation of water from the Nile into blood is a profound demonstration of God's power over creation. The Nile River was a vital resource for Egypt, symbolizing life and sustenance. By turning its water into blood, God is showing His supremacy over the natural world and challenging the Egyptian deities associated with the river.
This sign is not just a display of power but also a foreshadowing of the plagues that will come upon Egypt if Pharaoh refuses to release the Israelites. It highlights God's commitment to freeing His people and His willingness to use extraordinary means to achieve this goal. The act of turning water into blood serves as a warning and a testament to God's ability to alter the course of nature to fulfill His promises. Through these signs, God reassures Moses of His presence and support, encouraging him to carry out the daunting task of leading the Israelites to freedom.