Verbal reasoning questions are not restricted to the eleven plus. Many puzzles and tests have verbal reasoning style tasks but what are they?
It's all about using logic using English to solve problems. Cloze tests (short for closure) are when missing components in a sentence need to be completed. For example:
Choose the word in brackets which best completes this sentence. John couldn't (say, decide, know, want) whether to have chocolate or strawberry milkshake.
[The answer is decide]
Other questions might be identifying synonyms (matching words - tall/lofty) or antonyms (opposite words - high/low). There are many other types of verbal reasoning question, but not all are likely to be used in one test.
The eleven plus, grammar school entrance, test has a number of questions which test on knowledge as well as problem solving. The best way to prepare for these is to encourage extensive reading as this will help increase vocabulary as well as enhancing the ability to recognise appropriate sentence construction and grammar.
Verbal reasoning questions, like all tasks, only test one part of a person's skills and knowledge but they are extensively used in testing and recruitement and some familiarisation with questions is always good preparation. Find appropriate past papers and have some practice. You might even find them fun!