This verse from Psalm 59:9 is a powerful expression of trust and reliance on God, particularly in the face of adversity. Let's break down the meaning of each part:

"Oh, my Strength...": This is an address to God, recognizing Him as the source of the Psalmist's power, might, and ability to endure. It acknowledges that the Psalmist is not relying on their own resources but on God's inherent strength.

"...I watch for you...": This indicates an active, expectant waiting. The Psalmist isn't passively enduring the situation but actively looking to God for help, deliverance, and guidance. It implies a posture of prayer, alertness, and readiness to receive God's intervention. Waiting implies faith that God will act.

"...for God is my high tower.": This is a metaphor emphasizing God's protection and security. A high tower, in ancient times, was a fortified structure offering refuge from enemies. It suggests that God is a safe haven, a place of refuge where the Psalmist can find safety from danger and threats. It is an elevated position, difficult for enemies to reach.

Therefore, the verse as a whole means:

The Psalmist is acknowledging God as their source of strength and that they are actively waiting and watching for God to act on their behalf. They are confident that God will protect them like a high tower, providing safety and security amidst their challenges. This verse expresses a deep reliance on God's power and protection, particularly during times of trouble. It is a declaration of faith and a testament to the Psalmist's trust in God's ability to deliver them.

In essence, it's a powerful affirmation of faith:

God is the source of strength.
Faith requires expectant waiting and watching for God's action.
God provides a secure refuge from danger.

The Psalm was written by David at a time when King Saul was trying to kill him. Knowing that can shed further light onto this verse. David trusted that God would protect him from Saul.