This means that internal links on your website that is the anchor tags do not have title attribute or other links leading to various landing pages of your website have nothing to describe what the link is about or where it leads to. This often affects how Google bots view your various web pages and this can often lead to page mapping issues (wrong target page ranking).
Also links can influence click behavior for users hence it's advisable to have link titles to help users easily navigate your website. You can fix this by adding <a title="link_title"> to all anchor tags of your website.
SEO Doctor also offers expert service to fix this issues for you. You can reach out to me : grace[at]seodoctorapp.com