fix(i18n): Correct number & typo on zh-Hans i18n

[Def9Infinite]

Please check if the PR fulfills these requirements:

• [x] The commit message follows our guidelines.
• For bug fixes and features:
  • [x] You tested the changes.

Related issue (if applicable): GDQuest/learn-gdscript-translations#178

What kind of change does this PR introduce?

Fixing i18n issues in lesson 7.