You can get the text using the code :
String text = driver.findElement(By.cssSelector("p.font11.metadata_value")).getText()
The variable text will contain 639.78 MB value .
You can extract 639.78 from the text in several ways like :
text.split("\\s+")[0] // this will return 639.78
OR
you can use regular expressions for extracting number like ([0-9.]*).*
you can take help from this link if you are using regex
For having multiple <p>
like :
<li id="li1"> <div> <p class="font11 metadata_value">0 Views | 14 Downloads</p> <p class="font11 metadata_value">639.78 MB</p> </div> </li>
,
you can use xpath to get the text values.
driver.findElement(By.xpath("//li[@id='li1']/div/p[1]")).getText() // for first <p>
driver.findElement(By.xpath("//li[@id='li1']/div/p[2]")).getText() //for second <p>
driver.findElement(By.xpath("//li[@id='li1']/div/p[3]")).getText() // for third <p>
and so on ..
After getting the text of <p>
tag , you can extract the info using some regular expression.