Preunderstanding referes to all of our preconceived notions and understandings that we bring to the text, which have been formulated, both consciously and subconsciously, before we actuall study the text in detail.
Preunderstanding is formed by both good and bad influences, some accurate and some inaccurate. It includes all that we have heard in Sunday School, at church, in Bible Studies, and in our private reading of the Bible. However, preunderstanding of biblical texts are also formed by hymns and other Christian music,pop songs, jokes, art, and nonbiblical literature, both Christian and secular. Likewise, culture constantly creeps in.
It may also comes from our own theological bias. For example, there was a time when theology for me meant Dispensationalism. So it was natural for me to approach the text with Dispensational leanings. Anything that did not fit with the meaning I was looking for, I will just simply skip or ignore. If we want to find out the realy meaning of the Biblical text, we should free ourselves of those preconceived theological views.
The authors go on to say that "preunderstanding including culture (or theological views) is not inherently bad, but it can often skew our understanding of the Bible, leading us down the trail of misinterpretation. We do not want to abandon our preunderstanding, throwing all of our previous encounters with the text in the trash. What we do want to do is to submit our preunderstanding to the text, placing it under the text rather than over the text. We must be able to indentify our preunderstanding and then be open to changing it in accordance with a true serious study of the text."