To preserve kerning and the appearance of text objects, text in imported generic EPS or PDF files (that is, an EPS or a PDF created with an application other than Illustrator) is not imported as a single string of editable text.
To combine multiple text objects into a single text string, you can use the Selection tool (black arrow tool) to select the different type objects, choose Edit > Copy, switch to the Type tool and create a new area text object, and then choose Edit > Paste.