Why are there italicized words in the Bible?

Those words do not appear in the original text in the original Greek or Hebrew. The translators placed the words there in order for the verse to make sense. The original language may have used a case or form of a verb where there is not an English equivalent. For example, if the original language used the imperative (command) case of "do this", and the case also implies to "do this" forever; unless the translator adds the English in italics "forever", the reader will not know what is meant by the author.

.

Which makes more sense, the first or the second ?

Rev 22:2 In the midst of the street of it, and on either side of the river, the tree of life, which bare twelve fruits, yielded her fruit every month: and the leaves of the tree for the healing of the nations.

Rev 22:2 In the midst of the street of it, and on either side of the river, WAS THERE the tree of life, which bare twelve MANNER OF fruits, AND yielded her fruit every month: and the leaves of the tree WERE for the healing of the nations.

I have capitalised the words that were italicised in the KJV -

these word were added to make the sentence make sense !

May God bless you as you study His Word

<:)))><

In brief, it is because they appeared in the “Received Text” upon which the King James Version is based, but not in the Westcott and Hort text

those are words that were inserted after translation to make it make more sense. They didn't come through DURING translation but, of course, after reading it and studying it they put those words in so it would read easier and make more sense. :-)

The publishers should have an explanation in either the front- or back-matter.