This is a meaning to place an offering when the plate or basket is passed around while in Church. Typically Churches take up an offering on Wednesdays, Sunday morning and evening for covering the expenses of the Church operations. There are other giving opportunities as well within the Church, for the youth activities, missions to other countries, a building fund, single parents, feeding the homeless. This is all good, but there is a main reason for giving that supersedes the basic giving defined above.
The Lord outlines in the Word many times why it is for your benefit to give, because there is a divine law that is in place. The Tithe is normally 10% of your income, meaning you should give ten percent unto him as tithes and offerings and He will bless you many times over to meet your needs more abundantly than you could provide for yourself, by your own means and ways.
By giving Him the first part, you are keeping the Lord in first place in your life and counting on Him to cover you in all your ways, financially, emotionally, physically, protection and so forth. God sees your heart and where your desires are, everyday. There is much to say on this subject, I will provide some links for you to expand. Unfortunately, there are those who are wolves in sheep's covering and can take your money for no good reason and all the time you are manipulated into thinking they are acting on behalf of the Lord, when they aren't. The Bible speaks about these type of false teachers and pastors, in order for you to not be tricked, you need discernment, knowing the word of God staying in prayer, will give you wisdom when someone says something and in your spirit, there is a "check", this means beware. There is legitimate bountiful reasons to give, read the following scriptures;
See: Deuteronomy 15:10, Deuteronomy 16:17, 1 Chronicles 29:9, Proverbs 3:27,, Malachi 3:7, Malachi 3:10, Matthew 6:1, Luke 6:30, John 3:16, Acts 20:35, 2 Corinthians 9:6,10.