It sounds like the engine immobilisation system.
If the system recognises the code in your key then the light should come on for approx 3 seconds and then go out again.
If it stays on for more than a minute, or flashes for approx 1 minute and then at irregular intervals then either the system didn't rtecoginise the key code or a system fault is present.
Remove the key and try again.
If it keeps happening or the engine won;t start, get the car checked out by an expert.