Of course whatever the Bible says is true. But it’s not always literal. For instance, when Paul says in Ephesians that Jesus is the Cornerstone of the Church, he certainly means it—but not with complete literalness (e.g., that Jesus is literally a stone).
In which case, it's obvious to us that Paul does not mean the Jesus is literally building material. But, when God says there was the evening and morning of the day, why in the world would you over-think such a plainly worded statement? Of course He meant a DAY, as we understand it. He is God, and He made all we see, and more! He is easily able to do it in five minutes if He wanted to.
Look at the Chicago Statement of Biblical Inerrancy, which accounts for these things ... this is the second part ...
Chicago Statement on Biblical Hermeneutics
http://www.bible-researcher.com/chicago2.html
Article X
WE AFFIRM that Scripture communicates God’s truth to us verbally through a wide variety of literary forms.
WE DENY that any of the limits of human language render Scripture inadequate to convey God’s message.
This Affirmation is a logical literary extension of Article II which acknowledges the humanity of Scripture. The Bible is God’s Word, but it is written in human words; thus, revelation is “verbal.” Revelation is “propositional” (Article VI) because it expresses certain propositional truth. Some prefer to call it “sentential” because the truth is expressed in sentences. Whatever the term—verbal, propositional, or sentential—the Bible is a human book which uses normal literary forms. These include parables, satire, irony, hyperbole, metaphor, simile, poetry, and even allegory (e.g., Ezek. 16-17).
As an expression in finite, human language, the Bible has certain limitations in a similar way that Christ as a man had certain limitations. This means that God adapted Himself through human language so that His eternal truth could be understood by man in a temporal world.
Despite the obvious fact of the limitations of any finite linguistic expression, the Denial is quick to point out that these limits do not render Scripture an inadequate means of communicating God’s truth. For while there is a divine adaptation (via language) to human finitude there is no accommodation to human error. Error is not essential to human nature. Christ was human and yet He did not err. Adam was human before he erred. So simply because the Bible is written in human language does not mean it must err. In fact, when God uses human language there is a supernatural guarantee that it will not be in error.
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The first part I mentioned up above ...
Chicago Statement on Biblical Inerrancy with Exposition
http://www.bible-researcher.com/chicago1.html