A second helping of dessert (for example) is often shortened to seconds.

A second sitting is a later mealtime, where there is not space for all the diners to sit down at the same time.

Second best might describe a suit of clothes or be a second choice, where a number of options have been ranked in order of preference.

Second thoughts are often best
is a saying.  It is not always wise to act on impulse and do the first thing that comes into our heads.  Sometimes the first idea is the best, but it is worth weighing up the options.

I’ll second that means I agree.  In formal meetings it I the custom for one person to propose a motion or a candidate, then another has to second the proposal before a vote can be taken – perhaps by a show of hands.  (See my previous post.)

He’s been seconded to…
…a different workplace.  A secondment is a spell working away from one’s usual place of employment.

Any second now…
…something might happen!

(A second here is one sixtieth of a minute and a minute is one sixtieth of an hour.  Obviously?  But what about angles?  A second is one sixtieth of a minute and a minute is one sixtieth of a degree!)

Two to a pair is an idiom.  A pair is two as in shoes, gloves, socks and so on.  If two people are described as two to a pair, it usually means one is as bad as the other.

It takes two to tango.
A tango is a dance in which the partners hold each other close.  The saying means that if someone does not want to be led astray they can resist.

Standing at ten to two refers to the position of someone’s feet.  The numbers represent the time on an analogue clock face.

A second chance is something we often need if we have failed at something or done something wrong.

If we have been forgiven there is no record of our sin as far as God is concerned.  He has given us the chance to wipe the slate clean.

The prophet Jeremiah (who often gets a bad press) spoke the words of the Lord (Jeremiah Chapter 31 verse 34 (NIV)) “For I will forgive their wickedness and remember their sins no more.”  The link includes the whole of this verse and the context.  It is a wonderful promise to believers.  Jeremiah Chapter 31 verses 31-34