Strong's numbers are an easy way to search for information on the original Hebrew or Greek words they represent, without even knowing the original language alphabets. Not only can you use them to search for all the occurrences of a particular Hebrew/Greek word, but you can use them to look up definitions of those words in lexicons [foreign language dictionaries] that specialize in such things.
There is not a one-for-one correspondence between a Hebrew or Greek word and its English translation. Translators use variety of synonyms for the same word. Besides, the range of meanings of words in different languages is only rarely the same, making things even more difficult. For that reason knowledgeable people usually do word studies in the original languages, rather than trying to do something like "The Biblical Definition of 'Love.'"