In specific sentences/contexts you can translate it to would like to.
- Ik wil eten = I want to eat
- Ik wil graag eten = I'd like to eat (I think I want to eat please actually is closer, but this probably is less friendly than the Dutch sentence and it is a request, while the Dutch one could be, it can also simply be a remark. Because the Dutch sentence includes graag it's not impolite or blunt at all)
- Ik zou willen eten = I'd like to eat
- Ik zou graag willen eten = I'd love to eat
- Ik zou willen eten alstublieft = I'd like to eat please (this is more like a request, e.g. addressing a waiter)
- Ik zou heel graag willen eten = I'd like very much to eat
I'd bet it's cognate to German "wollen" (which becomes 'ich will, du willst, er will'), and the root of 'will' as 'want' (think 'as you will' or 'Thy will be done' or your last will and testament--i.e., the final things you want done).
And I'd hazard that 'will' as a future 'to be' is an abstraction from 'I want this [and intend to get it in the future]' to 'This is a certainty in the future.'
The future sense of "will" was originally not used in the first person; that was (and in some dialects still is) handled by "shall" instead. So it's interesting psychologically: by default, you/they will because you/they want to; but I/we shall because I/we ought to. (That's the original meaning of "shall", still the meaning of the German cognate "sollen" and preserved in English in the past subjunctive form "should".)
This is overly simplified; there's a great explanation by Fowler that I'll try to find.