This type of financial instrument has a limited life and can be converted into new ordinary shares in the company at some time in the future at a fixed price.
Warrants have similar characteristics to subscription shares. They don’t have the same rights as ordinary shares (e.g. they are not entitled to any dividends before they are converted into the ordinary shares). They are also much higher risk than ordinary shares, as you may not want to convert them into new ordinary shares if you can buy these on the stock market more cheaply. They can therefore expire worthless and you could lose all the money you paid for them.
See also subscription shares.