Field 5263 and 5267 are both part of spouse net income. They are needed when the tax payer (not the spouse) is a new immigrant (so tax payer has an entry date on page 1 of T1) in the tax year. Field 5263 is spouse's net income after tax payer's entry date; Field 5267 is spouse's net income before tax payer's entry date.
You can find field 5263 and 5267 when you click spouse net income field on page 1 of T1. See this screenshot
Last and most important, please make sure the following:
Field 5263 + Field 5267 must EQUAL to field 236 (spouse net income in same dialog)