To correct the error in the sentence "There is many things to be today," we need to pay attention to the subject and verb agreement.
Step 1: Identify the subject of the sentence. The subject here is many things, which is plural.
Step 2: Determine the correct verb form. Since the subject is plural, we should use are instead of is.
Corrected Sentence: "There are many things to be today."
Now the sentence is grammatically correct as both the subject and verb agree in number!