Does the following sentence still understood if I delete "he is" in the following sentence?
Hi, Meriem—Your question suffers from two major grammatical errors, as well as a tense error and an error of redundancy.
First, when you ask a question in English and use "do"-support, the main verb should be in its base form ("understand," not "understood").
Second, sentences don't understand things. People understand sentences. You need to use the passive voice ("be understood").
Third, you should use "Will the following sentence be understood" because the processing time is in the future relative to the time of composition.
Fourth, since you have used the phrase "the following sentence" as the subject, you should not redundantly say "in the following sentence" at the end.
- Will the following sentence be understood if I delete "he is"?
The answer is that the result of deleting "he is" will be an ungrammatical sentence, whether or not anyone grasps your intended meaning.