I suppose it all depends on your perspective, but to me, actually, it's number 3. It means useful.
I can see where the confusion would arise though, because these definitions are related. The key thing to remember about all of the definitions of practical is that they are very deeply rooted in reality and are not things that are theoretical.
There are many ways to look at it, but these are generally things that are practiced. They often have practical applications, whether to a given situation/context or occupation or to everyday life (i.e., in practice).
Things that are practical can be nearly assured to work; they can be very easy to implement; and they have more widespread applicability.
I think my success in trying to explain to you, in practice, what practical means will be largely dependent on how well I define the terms, from a practical (number 1, connected to real things) point of view.
Practical can mean it's practically (number 2, likely to work)
near certain that a given thing will happen.
I don't think it's practical (number 4, sensible)
for me to proceed until I'm able to demonstrate, in practical (number 3, useful) terms, just how practical (number 5, good at making things) I can be when it comes to explaining the meanings of words in context.
I've gained practical (number 1, connected with real
experience as a writer through teaching ESL/EFL.
(number 3, useful)
for one to acquire skills that can be practically (number 2a, likely
practiced in one's everyday life.
There are practically (number 2, almost totally/nearly)
an infinite number of subtlety-different, yet at the same time, closely related, definitions
of the world practical; so much so that I wasn't sure that I was being practical or thinking practically
to try to use so many in a single example.