Blood is a body fluid which is involved in the transportation of essential nutrients, Oxygen and carbon dioxide throughout the body.
It consists of Haemoglobin which gives it a red colour.
When blood is acidic:
The concentration of carbon dioxide increases when blood is acidic.
This results in decreased of the blood.
It causes the release of oxygen from the Haemoglobin proteins and thus, the binding of oxygen with Haemoglobin decreases, resulting the body parts get lesser oxygen than required.