Natal Venus is the sign where your Venus was placed during birth time, and from there other houses are calculated clock-wise.
If you were born with Venus in Libra, then your natal house is Libra (Thula Rasi) and during transit, Venus forming conjunction (in Libra), sextile (aspect of 60° which are Leo and Sagittarius in this case), square (aspect of 90° which are Capricorn and Cancer here), trine (aspect of 120° which are Gemini and Aquarius here), opposition (aspect of 180° which is Aries here) are discussed in this article.
Conjunction is transiting through same sign as in birth chart, sextile is transiting 3rd or 11th house, trine is transiting 5th or 9th house, opposition is transiting 7th house from natal sign.
Transit Venus conjunct Natal Venus : The aspect characterizes grace and harmony in social and artistic expression. This is the time to take initiative in romantic and love relationships and buying good dresses, cosmetics, things to decorate home, objects of art and musical recordings. A good time for casual get together, parties and entertainments. Afflictions to this conjunction produce sensuality and extravagance.
Transit Venus Sextile Natal Venus : Ease, contentment, insight in artistic and social endeavors characterize this transit. The native has congenial relationships with every one. Plans and business proposals are easily accepted. The native exhibits friendliness and grace in his manners and speech. A favorable period to enter into love. The native may have good public relations and find it easy to deal with women and have recreational trips.
Transit Venus Square Natal Venus : Self indulgence, extravagance, misplaced sympathy and emotional hyper sensitivity characterize this transit. The native’s misplaced sympathies allow others to make use of him for their benefit. Not a good period to relate oneself with women. The native has to beware of extravagance and self indulgence. Normally this transit is not so bad but requires caution in the above described areas.
Transit Venus Trine Natal Venus : Social, artistic, musical, entertaining and sports activities characterize this transit. This aspect tends to attract money and persons and is a smooth and trouble free period. Business and romantic opportunities arise through social activities. A good period for business related to art, music, entertainment and luxury goods. Musical and artistic endeavors gain public recognition and approval. A favorable period for dealing with women and entering into love.
Transit Venus Opposition Natal Venus : Though it is an opposition but not bad and indicates excessive social activity. The native is extravagant and involves himself in excessive sex. The native should be compromising with loved ones at this time. The native should not sign any contracts now without examining the minute details of it. The native is required to use tact and diplomacy and avoid to take it for granted attitudes.