The noun and verb can be used with concrete nouns such as food, money, friends, as well as abstract things, such as knowledge, love, courage. The noun and verb "lack" is interesting because it can mean two things. For example, 1) it can mean that something that is needed or wanted is absent = there isn't any, or 2) it can mean that something that is needed or wanted is in short supply = there isn't enough 1) I lack the knowledge and skill to build a computer (I have no knowledge or skill) 2) The people in this area lack food (they don't have enough food) The word lack is a little formal or advanced but it is completely appropriate in your sentence. To be less formal we could say "don't have any food or do not have enough food". We would need another sentence to tell us if lack meant "none or not enough". For example, "There was a drought this summer, so none of the plants/crops grew (or only some of the plants/crops grew).

It’s perfect. The refugees lack food. (Good) The refugees don’t have food. (Common. More familiar) I lack the money to take as many courses as I’d like.

"Lack" is used to describe tangible things and intangible things. There is no difference. We can lack confidence, motivation, etc. "If any of you lack wisdom, he should ask for it" in prayer.... We can lack food, water, spare parts (machinery), etc. E.g. I have this and that, but I am lacking..... I lack a nut/bolt of this size. Do you have one that will fit? Or you can say 'shortage' or 'short'. I am short of this part. I have a shortage of ……