This plant has spring up from a dry area that is sparsely covered. It has distinctive spiky leaves which resemble a Holly but so far I've failed to match it. There isn't anything in the vicinity where I found this that has a matching leaf.
This appears to be a holly seedling, most likely Ilex aquifolium; these are commonly dropped by passing birds and germinate readily. Ilex are dioecious plants, and the only way to tell whether a plant is male or female is to wait and see if it produces berries, or examine the flowers closely when it's old enough to produce some - info on that here https://www.thespruce.com/difference-in-male-and-female-holly-bushes-2132269
They grow at a reasonable rate, getting up to 12 metres in height with a spread of 4-8 metres - deciding whether you want to keep it or not is best done early, because removing them once they're a reasonable size is not a comfortable experience!