There is very good evidence that salt can make your blood pressure higher. High blood pressure has many bad effects. It makes it more likely that you will have a stroke, a heart attack, develop kidney failure. High blood pressure can also cause damage to other blood vessels including those in your eyes.
If you already have high blood pressure and are on treatment for it, then lowering your salt intake can help to reduce the amount of medication that you need to control your blood pressure.
Read what the Blood Pressure Association says about salt here.
Read what the British Hypertension Society says about salt here.