The Price Alert indicator plays sound alerts if the market price reaches certain levels which are set by the trader. There exist three types of alerts: the first one is used if the market price rises above the specified level (it is shown as a green line on the chart); the second one is used if the market price falls below a certain level (it is shown as red line on the chart); last but not least the third one is used if the market price reaches a strictly specified level (it is shown as a yellow line on the chart).
When you use the function of sending the signal by email, you should not forget to configure the SMPT server and to define the email address in your MT platform options window.
The Price Alert indicator does not produce alerts to buy or sell. You can just use it if you need a sound alert on reaching certain price levels. Then you can use the moment to work with the market. You can set some input parameters at zero value to deactivate the corresponding signals.
You can download the indicator here: https://www.mql5.com/en/code/13192